Air WELLography First Edition

Particulate Matter Derived from Plants and Animals

Particulate matter derived from plants and animals includes pollen and pet dander. These particles often contain reactive surface proteins, which when aerosolized cause adverse immunological or allergic responses in sensitive individuals. According to the U.S. National Institute of Allergy and Infectious Diseases (NIAID), symptoms of environmental allergies include watery eyes, stuffy/itchy nose, coughing, and asthmatic symptoms such as tightness in the chest.³⁵

1. Plant- and Animal-based Particulates

The most common plant-based particle is pollen. Pollen particles are produced by the male reproductive organs in plants and are freely disseminated in the atmosphere as a method of plant reproduction. Pollen particulate can provoke an immune response in some people, thereby inducing an allergic reaction that includes sneezing and cold-like symptoms. Due to pollen’s association with the reproductive cycles of plants, the type and amount of pollen in the air vary by season.³⁶

There are currently no broadly accepted standards explicitly addressing pollen, and methods of monitoring pollen vary by organization. The NAB has a certified testing protocol that identifies the species from which the pollen originates. However, due to the difficulty in conforming to this protocol, there are fewer than 100 sampling sites in the U.S.³⁷ The sampling stations report pollen counts per cubic meter (pcm), as well as the predominant species. The NAB has established qualitative ratings based on pollen counts: 1) “low,” roughly defined as less than the 50th percentile; 2) “moderate,” levels between the 50th and the 75th percentile; 3) “high,” levels between 75th and 99th percentile; and 4) “very high,” levels as those above the 99th percentile.³⁸ In Europe, the Medical University of Vienna is developing a continental pollen map for different plant sources. The methodology for developing this map will establish a threshold for adverse reactions using information collected from pollen diaries kept by 29,000 seasonal allergy sufferers.³⁹

Health Effects

Respiratory System

Asthma. The AAAAI notes that proteins in pet dander, saliva, urine, and skin flakes can aggravate asthma in susceptible individuals.⁴⁰ Additionally, the Asthma and Allergy Foundation of America (AAFA) recognizes pollen as a trigger for asthma in susceptible individuals.⁴¹

Allergies. The AAAAI notes that the proteins in pet dander, saliva, urine and skin flakes can cause an allergic reaction in susceptible individuals. The symptoms may include sneezing, itchy and watery eyes, and sniffling.⁴⁰ The symptoms of pollen allergies may include coughing, dark circles under the eyes, itchy nose and/or throat, postnasal drip, runny or stuffy nose, sneezing, and swollen, itchy, and watery eyes.⁴¹

Nervous System

Weakness and depressed mood. Psychoneuroimmunology and genetic research suggest that allergic reactions to ragweed pollen can cause biochemical changes that directly affect the central nervous system. The release of inflammatory cytokines (small proteins released by immune cells to recruit a reaction to a stressor or damage) directly affects the central nervous system, inducing mental fatigue, lethargy, and depressed mood, which ultimately affect the overall ability to concentrate or be productive.⁴²

Solutions

1. Media Filtration

Filtering incoming air is an effective defense against plant- and animal-based allergens. Filters with a minimum efficiency reporting value (MERV) rating of one to four are targeted to remove particles, such as pollen, that are 10 µm in diameter or larger. Filters with a rating of eight will remove at least 70% of all particles that are 3–10 µm in diameter, which includes cat and dog dander.⁴³ Additional defenses against particulates include not allowing pets on furniture, routine vacuuming of furniture and carpets, or having pets remain outside.⁴⁴

2. Dust Mites, Cockroaches, and other Pests

Although neither dust mites nor cockroaches are inherently dangerous animals, their droppings contain allergens that can trigger an allergic response in susceptible individuals (Figure 3).⁴⁵ ⁴⁶ In addition to being allergens themselves, pest feces can act as carriers for other pathogens and toxins and are a major cause of asthma prevalence.⁴⁵ ⁴⁶ Other pests, especially rodents, produce dander and droppings that similarly cause adverse health effects in humans.⁴⁵

FIGURE 3: SYMPTOMS DUE TO EXPOSURE TO DUST MITES AND COCKROACHES.⁴⁵ ⁴⁶

There are currently no broadly accepted air quality standards specifically addressing allergenic particulates caused by indoor pests. However, the Consumer Product Safety Commission (CPSC) and the American Lung Association (ALA) advise that indoor spaces be regularly cleaned to prevent the spread of these pollutant sources.⁴⁵

Health Effects

Respiratory and Immune System

Allergies. Proteins in dust mite waste, as well as cockroach bodies, feces, and saliva can cause allergic reactions in susceptible individuals.⁴⁷ ⁴⁸ Individuals with asthma, chronic stuffy nose or sinus infection, ear infection, and skin rashes are more likely to be allergic to cockroaches, and those with chronic severe bronchial asthma are most likely to have cockroach allergies.⁴⁸

Asthma. The AAFA notes that materials in cockroach bodies, feces, and saliva can trigger asthma in susceptible individuals. Individuals allergic to cockroaches can develop acute asthma attacks after inhaling air that contains cockroach allergen, with symptoms lasting potentially for hours.⁴⁸ About 23% to 60% of people with asthma who live in urban environments also have a sensitivity to cockroach allergens.⁴⁸

Solutions

1. Dehumidification

Controlling indoor humidity with dehumidifiers can help to limit the growth of dust mites.⁴⁹ ⁵⁰ Additionally, dehumidification is recommended by the Agency for Toxic Substances and Disease Registry (ATSDR) to improve air quality and reduce airborne allergens.⁵¹

2. Source Reduction

Combating the infiltration of pests without the use of products that may exacerbate other respiratory symptoms requires a holistic approach to pest management. Integrated pest management (IPM), the method currently recommended by the EPA, involves removing sources of pest food, water, and shelter by routine inspection, maintenance of facilities, and a regular sanitation schedule.⁵²

3. Pest Prevention

Maintaining a hygienic environment helps to prevent pest problems. Some common preventive measures include ensuring that all food and water is stored in bags or containers and is not left out in open areas. In addition, fixing water leaks, limiting clutter, and sealing holes where pests can live and breed helps reduce the likelihood of dust mite and cockroach problems.⁵²

Microbial Pathogens

Microbial pathogens of viral, bacterial, and fungal origin can directly cause a variety of adverse health conditions in susceptible individuals. The immune system is the primary means of defense against pathogens and other stressors. Exposure to pathogens can cause illnesses that range from mild inflammation to life-threatening medical conditions. Poor air circulation and excessive humidity are important variables that contribute to the accumulation and growth of microbial pathogens indoors.

1. Bacteria

Certain species of bacteria can cause pulmonary inflammation and may lead to infection. Bacterial bioaerosols are suspensions of microscopic biological particles that thrive in conditions with poor air circulation and ventilation. They are responsible for illnesses such as tuberculosis and Legionnaires’ disease.⁵³

Health Effects

Respiratory System

Pneumonia, respiratory failure, death. Legionnaires’ disease is a potentially fatal form of pneumonia caused by inhaling the Legionella bacteria in aerosol form, commonly in mist contaminated with the bacteria.⁵⁴ Legionella can cause serious and life-threatening complications, including respiratory failure, septic shock, and acute kidney failure.⁵⁴ The CDC estimates that 8,000 to 18,000 hospitalizations occur in the U.S. due to Legionnaires’ disease, of which 5% to 30% result in death.⁵⁵ Common sources of Legionella are cooling towers, hot tubs, large central air-conditioning systems, and fountains.⁵⁶

Tuberculosis (TB). TB is spread through the air from person to person when an infected individual coughs or sneezes and generates airborne water droplets.⁵⁷ The bacterium is carried in the droplets of water expelled from the nose or mouth, which can then be inhaled by an uninfected person nearby. Once aerosolized, TB bacteria can stay suspended in the air for several hours.⁵⁸ Up to 40,000 droplets are expelled in a single sneeze, and it only takes as few as 10 microbes to cause an infection.⁵⁹

In the early 1900s, tuberculosis caused one out of every seven deaths in the U.S.⁵⁷ TB symptoms include fever, chest pain, and a bad cough lasting three weeks. Many people who have tuberculosis remain healthy as the disease lies dormant, but their condition rapidly deteriorates if their immune system becomes compromised.⁵⁷

Immune System

Humidifier fever. Humidifier fever is a form of sick building syndrome of mixed etiology that can be caused by bacteria in the humidifier system. It includes flu-like symptoms, such as fever, headache, chills, coughing, and tightness in the chest. Humidifier fever usually occurs a few hours after exposure and is often due to the bacteria found in the humidifier reservoir.⁶⁰ ⁶¹

Solutions

1. Dehumdification

Controlling indoor humidity via the use of dehumidifiers can help to limit the growth of problematic bacteria.⁴⁹ Additionally, dehumidification is recommended by the ATSDR to improve air quality and reduce airborne allergens.⁵¹

2. Source Control

Any reservoirs used for containment of water that will be aerosolized (e.g., a humidifier) should be cleaned and properly dried between uses to prevent bacterial growth.⁶²

3. Media Filtration

Filters with MERV ratings of 13 to 16 will remove more than 90% of all particles that are 0.3-1 µm in diameter, which includes the majority of bacteria.⁴³

4. Ultraviolet Germicidal Irradiation

In a double-blind, multiple crossover study of office buildings, the use of ultraviolet germicidal irradiation (UVGI) effectively destroyed 99% of the microbial contaminants on irradiated surfaces in the ventilation system.⁶³ In the study, airborne bacteria levels were lowered by 25% to 30%, and study participants reported reduced work-related respiratory and mucosal symptoms when UVGI was used.⁶³

2. Viruses

Viruses, like airborne bacteria, can spread via aerosolization.⁶⁴ Once inhaled, viruses can lead to infections such as the common cold, influenza, mumps, and varicella, among other illnesses. Viruses are generally less than 0.1 µm in size but are often found in suspended water droplets that are up to five µm in size, meaning that viruses can sometimes be removed with media filters. However, if they are aerosolized, filtration is more difficult.⁶⁴

Between 1976 and 2006, influenza and influenza-related respiratory illness were responsible for 3,000 to 49,000 annual deaths in the U.S. alone. Currently, 5% and 20% of Americans contract the flu each year.⁶⁵ Children, the elderly, pregnant women, and those with weakened immune systems are especially susceptible to influenza.⁶⁶

Health Effects

Respiratory System

Influenza. Influenza, or the flu, is an acute, contagious viral infection. It is caused by a variety of mutations of the influenza virus and typified by an inflammation of the respiratory tract, resulting in fever, chills, muscular pain, and fatigue.⁶⁵ Infected individuals can spread viral particles, which become aerosolized when a person coughs, sneezes, speaks, or merely breathes.⁶⁵

Asthma. Inhalation of airborne viruses is a known trigger for acute asthma symptoms and may increase the risk of developing chronic asthma, especially in young children.⁶⁷

Immune and Integumentary Systems

Varicella (chickenpox). Varicella, often referred to as chickenpox, is a common and incredibly infectious viral disease that affects both children and adults.⁶⁸ The virus responsible causes both varicella and shingles. Varicella results in an itchy, blistery rash that lasts about a week and at times involves a fever or other symptoms. It is spread through the air when an infected person coughs or sneezes.⁶⁸ Shingles is an outbreak of blisters or rashlike plaques on the skin marked by a painful, tingling, burning sensation and can last up to five weeks.⁶⁹ Once a person has had varicella, they are at risk of developing shingles later in life.⁶⁹

Immune and Digestive Systems

Mumps. Mumps is a viral disease that causes painful swelling of the saliva-producing glands in the mouth. There is no specific treatment for ridding the body of the disease, and treatments instead focus on controlling the symptoms with pain-relieving medication.⁷⁰ Mumps is transmitted via saliva or mucus droplets when an infected person talks, coughs, or sneezes.⁷¹

Nervous System

Cognitive disorders. Exposure to the influenza virus during pregnancy may increase an infant’s risk of later developing bipolar disorder by four-fold and schizophrenia by three-fold, which may result from the activation of genes that increase the susceptibility for these disorders.⁷²

Solutions

1. Ultraviolet Germicidal Irradiation

Because of their small size, viral particles, are difficult to filter out of the air. However, ultraviolet germicidal irradiation has been shown to kill or inactivate a range of airborne viruses thorough sterilization and it can limit their prevalence in ambient air and on surfaces.⁷³ ⁷⁴

2. Media Filtration

Filters with MERV ratings of 17 or higher will remove at least 99.97% of all particles that are less than 0.3 µm in diameter, which can include viruses in airborne form.⁴³

3. Fungi (Mold)

In the natural environment (outdoors), mold is essential for breaking down dead plant material. However, it may become a health hazard in indoor environments.⁷⁵ Mold will grow anywhere that moisture and a food source are present, including on any organic matter, wooden wall studs or sheetrock.⁷⁵ Mold reproduces by releasing tiny spores into the air. Therefore, if mold is present near an air intake duct, it can get inside and circulate throughout a building.

To date, there is no standard method for the detection and analysis of indoor mold, making interpretation of test results highly variable. An assessment of airborne concentrations of pathogenic fungal microorganisms is troublesome and can be inaccurate and misleading, as some pathogenic microorganisms may be hazardous at very low levels, while others may only become hazardous at high levels. Also, while some mold spores are resilient, others may become inert during handling and sampling, thereby distorting the findings.

In non-culture-based methods, such as microscopy and flow cytometry, microorganisms are identified and quantified regardless of whether they are dormant or deceased.⁷⁶ The sampling time can vary over a wide range, yet the results can be quickly available. However, these results do not provide information about the possible toxic or allergic components related to the detected microorganisms. Furthermore, the procedures are time intensive and expensive. Analyses that detect the DNA, RNA, or specific proteins in molds or bacteria (e.g., polymerase chain reaction or immunoassays such as the Western blot) can be used to detect and identify non-culturable fungal species, while biomarkers for specific fungal biomass (essentially, fungal metabolites) can be used to measure and estimate actual fungal exposure.⁷⁶

The EPA and the U.S. Department of Housing and Urban Development developed the Environmental Relative Moldiness Index (ERMI) as a metric for assessing relative indoor air quality in the American Healthy Homes Survey.⁷⁷ ERMI analyzes dust collected from buildings for mold species and ranks it for potential risk and associated health effects (Figure 4).⁷⁷

FIGURE 4: MOLDINESS INDEX IN U.S. HOMES.⁷⁷

Health Effects

Respiratory and Immune Systems

Asthma. The AAFA and the EPA note that inhaling the spores of mold and mildew can trigger an asthma attack in individuals who are sensitive to molds.⁷⁸ ⁷⁹

Allergies. The AAFA notes that inhaling the spores of mold and mildew exacerbates allergies in susceptible individuals.⁷⁸ The symptoms of mold allergies include congestion, dry and scaling skin, itching, nasal discharge, and sneezing. Individuals who are allergic to pet dander or pollen are more likely also to be allergic to fungi.⁷⁸

Hypersensitivity pneumonitis. Hypersensitivity pneumonitis is a lung disease that can result from the inhalation of mold particles.⁸⁰ The ALA notes that the inhalation of mold spores causes inflammation of the lung and respiratory tract tissues.⁸⁰

The onset of hypersensitivity pneumonitis in indoor settings has been linked to air-conditioning units and humidifiers contaminated with bacteria and molds.⁸¹ Fungi that produce hypersensitivity pneumonitis include Aspergillus, a mold that is dangerous whether inhaled or ingested. Stachybotrys, known as “black” or “toxic” mold, and Penicillium are also known to cause hypersensitivity pneumonitis through the emission of mycotoxins.⁸¹

Respiratory System

Impaired respiratory function. Biological aerosols such as mold may cause impaired respiratory function.⁸² A study that administered questionnaires to nearly 15,000 parents or guardians of children found that the prevalence of all respiratory symptoms was consistently higher in children who lived in interior spaces with reported molds or dampness.⁸² Additionally, research with 269 healthy, non-asthmatic adults found an association between indoor mold exposure and reduced lung function, especially among female participants.⁸³

Bronchopulmonary aspergillosis. Bronchopulmonary aspergillosis is a fungus-induced disease that is primarily found in the respiratory tract.⁸⁴ ⁸⁵ The AAFA notes that the spores of mold and mildew can cause bronchopulmonary aspergillosis in individuals who are sensitive to mold.⁷⁸

Allergic fungal sinusitis. A 2000 study notes that inhaling fungal spores can cause allergic fungal sinusitis in susceptible individuals. Some of the symptoms include nasal polyps, rhinosinusitis, and occasionally proptosis.⁸⁵ Additionally, a 2016 review exploring the health effects of fungi exposure on humans indicated the relationship between indoor fungal exposure and the development of allergic fungal sinusitis in individuals with weakened ability to respond to the presence of fungi.⁸⁶

Humidifier fever. Humidifier fever is a form of sick building syndrome that can be caused by mold spores in the humidifier system.⁶⁰ It includes flulike symptoms such as fever, headache, chills, malaise, cough, and tightness in the chest. It usually occurs a few hours after exposure and is often due to the fungi found in humidifier reservoirs.⁶⁰

Nervous System

Headaches. The EPA notes that when there is mold growing indoors, one of the more common reaction symptoms is a headache.⁸⁷

Diminished neurobehavioral parameters. Studies investigating the effects of mold exposure on neurobehavioral function have found that those exposed to mold experience decreased function in regards to balance, reaction time, blink-reflex latency, color discrimination, visual fields, and grip.⁸⁸ ⁸⁹ Notably, individuals with mold/mycotoxin exposures experienced similar neurobehavioral impairments as those who experienced adverse reactions to various chemical exposures.⁸⁹

Solutions

1. Media Filtration

Filters with MERV ratings of seven or higher will remove at least 50% of all particles that are 3–10 µm in diameter, which includes mold spores.⁴³

2. Source Control

Any reservoirs used for the containment of water that will be aerosolized (e.g., a humidifier) should be cleaned and properly dried between uses to prevent bacterial growth.⁶²

3. Ultraviolet Germicidal Irradiation

UVGI and ultraviolet emitters can destroy airborne mold spores and stop fungal growth through sterilization.⁹⁰ In a double-blind, multiple crossover study of office buildings, the use of ultraviolet germicidal irradiation (UVGI) effectively destroyed 99% of the microbial contaminants (including mold) on irradiated surfaces in the ventilation system. Study participants reported reduced work-related respiratory and mucosal symptoms when UVGI was used.⁶³ Additionally, a case study of UVGI efficacy in a classroom setting found that compared to the control group, the UVGI classroom experienced significant reduction in total bacterial concentration in three of the four sampling months, indicating the potential for this technique in schools and other buildings.⁹¹

4. Dehumidification

The EPA notes that controlling indoor humidity can prevent the establishment and growth of mold.⁹² The agency recommends keeping indoor humidity levels below 60%, and ideally between 30% and 50%.⁹² Dehumidification is also recommended by the ATSDR to improve air quality and reduce the potential buildup of airborne allergens.⁵¹

Particulate Matter

Particulate matter air pollution is a complex mixture of small solid particles and liquid droplets in the air. Inhaling elevated levels of particulate matter have been shown to lead to various adverse health effects.⁹³

Particulate matter can contain elemental and organic carbon, salts, mineral and metal dust, ammonia, and water, which coagulate together into tiny solids and globules.⁹⁴ Both human-made (anthropogenic) and natural sources emit particulate matter or gaseous components that react in the air to form particulate matter. Particulates vary in size, shape, density, and chemical composition and are distinguished by aerodynamic diameter. Those designated as inhalable coarse particles have diameters larger than 2.5 µm and smaller than 10 µm (known as PM10), while fine particles have diameters of 2.5 micrometers and smaller (known as PM2.5). Ultrafine particles (UFPs) are of nanoscale and have diameters smaller than 0.1 µm (≤ 100 nanometers).⁹⁴ Fine particles are more easily measured than ultrafine and form the basis for many air quality recommendations due to their significant health impacts.

FIGURE 5: EXAMPLES OF COMMON PARTICLE SIZES.⁹⁵

The size of particulate matter largely determines where in the respiratory system the particles are deposited (Figure 6).⁹⁴ Because of the filtration provided by the nasal-pharyngeal and tracheobronchial regions, inhaled particulate pollution concentration is somewhat diminished by the time a particle reaches the deepest region of the lungs. The filtration provided by the body is more efficiently geared toward particles in the coarse particle range. Although ultrafine particles are not considered any more or less toxic than larger particles, concern arises from the more significant number of particles needed to create a similar mass concentration, thereby increasing the potential for damage or adverse effects.⁹⁴

FIGURE 6: LOCATION OF PARTICLE INTERACTION WITHIN THE AIRWAY.⁹⁶

1. Coarse Particulate Matter (PM10)

Coarse particulate matter, known as PM10, refers to particles 10 µm in diameter or smaller.⁹⁴ Due to the relatively larger size of the particles, PM10 is generally trapped in the head and upper airway region of the body and does not penetrate as deeply into the lungs as fine (PM2.5) or ultrafine particulates, which is why they are less of a health concern.⁹⁴ Nevertheless, coarse particles have been associated with negative health effects. A study investigating the effects of Saharan dust on daily mortality rates in Barcelona found an 8.4% increase in mortality with a 10 µg/m³ increase in PM10. The simultaneous increase in PM2.5 did not lead to an increased mortality on Sahara-dust days.⁹⁷ A study across 112 U.S. cities, analyzing the effects of particulate matter on mortality found a stronger than expected association between coarse particles and death.⁹⁸ The study suggested that regional differences in the toxicity of coarse particles and the observed effects on health varied by area and did not necessarily follow the same pattern of variance as PM2.5.⁹⁸ This point was expanded upon more recently in laboratory research that showed that PM10 is likely to generate a more generic symptomatic effect, while the smaller PM2.5 is likely to be more reactive at the cellular level.⁹⁹

When a particle is not formed by secondary gases, its size is directly attributable to the amount of energy used to generate it, i.e., the more energy used, the smaller the particle created.⁶⁴ When particles are mechanically generated from construction, agricultural, road traffic, volcanic and other sources, they tend to be larger (closer to 10 µm in diameter or more) and fall into the coarse (PM10) category. When the National Ambient Air Quality Standards (NAAQS) were established in 1971, the Total Suspended Particulates (TSP) limit was set at 260 µg/m³ on average over a 24-hour period (not to be exceeded more than once per year) and at 75 µg/m³ on average over a year. In 1987, PM10 replaced TSP as the standard of measurement, and the 24-hour value was set to 150 µg/m³, which is not to be exceeded more than once per year, on average over a three-year period. The annual limit for PM10 was removed as of 2006.¹⁰⁰ The WHO’s expanded guidelines for PM10 from 2005 recommend a stricter limitation of 50 µg/m³ for a 24-hour period and 20 µg/m³ for a year.¹⁰¹ The U.S. Occupational Safety and Health Administration (OSHA) recommends a time-weighted average for respirable particles not to exceed 5,000 ppm during any eight-hour work shift of a 40-hour workweek.¹⁰²

Health Effects

Respiratory System

Asthma. A bidirectional case-crossover and time-series analysis found a 14% to 18% increase in asthma hospitalizations among 6-12-year-old children in Toronto between 1981 and 1993 during increased exposure to PM10, an increment of 8.4 µg/m³ over an average of six days. The effects remained after adjusting for specific gaseous pollutants (NO2, CO, SO2, O3) as well as for PM2.5.¹⁰³ Additionally, exposure to PM10 may influence the risk of asthma development. A systematic review and meta-analysis of 41 studies exploring the relationship between exposure to traffic-related air pollution and asthma found a significant association between exposure to PM10 and risk of developing childhood asthma.¹⁰⁴

Respiratory mortality. A study analyzing data from 112 U.S. cities found an increase in respiratory mortality by up to 1.68% and a 0.98% rise in all-cause mortality (which varied by climate zone) associated with increased levels of particulate matter.⁹⁸ The findings made the distinction between coarse and fine particles with the coarse particle findings being higher than previously thought.⁹⁸ A study exploring the health effects of air pollution in Europe and North America found that among cities with available air pollution data, the combined effect of PM10 on all-cause mortality across all ages ranged from 0.2% to 0.6% for a 10-µg/m³ increase in ambient PM10 concentration.¹⁰⁵

Cardiovascular System

Decreased heart rate variability. Heart rate variability (HRV) is a measure of cardiac autonomic balance, and decreased levels of HRV are associated with an increased risk of cardiac mortality.¹⁰⁶ A study involving 19 nonsmoking patients with known coronary artery disease living in California’s Coachella Valley, a desert region with high PM10 values, found an association between HRV and PM10 levels. The observed HRV values, including time-domain, geometrical and frequency-domain HRV variables, suggested a close, timely effect between PM10 exposure and decrease in HRV.¹⁰⁶

Another study found similar decreases in HRV variables associated with a 1 µg/m³ increase in PM10 in asthmatic patients over a 12-week period.¹⁰⁷ While clear changes were observed in HRV, no diminishment in respiratory function was found to be associated with fine PM2.5.¹⁰⁷

Coronary heart disease. A cohort-study followed 3,239 adults for 22 years, measuring monthly levels of air pollutants and asking subjects to fill out and update lifestyle questionnaires.¹⁰⁸ Using a single-pollutant model, the risk for fatal coronary artery disease in women was 38% higher with every 10 µg/m³ increase in PM10. No similar association was found in males, however.¹⁰⁸ It has been found that the elderly and immunocompromised are more likely to suffer a cardiac event associated with PM10 exposure.¹⁰⁹

Solutions

1. Media Filtration

Filters with MERV ratings of eight or higher will remove at least 70% of all particles that are 3–10 µm in diameter, and those with a rating of 12 or higher will remove at least 90%.⁴³

2. Source Reduction

By eliminating particulate matter generators, such as tobacco smoke and indoor combustion of biofuels, and by ensuring that all ventilation systems are in proper working order, the amount of particulate matter indoors can be greatly reduced.¹¹⁰ Additionally, the removal of permanent carpets prevents re-entrainment of particles during cleaning.¹¹⁰

3. Entryway Walk-Off System

Walk-off mats are a useful and simple means of preventing particulate matter from being carried indoors on the soles of shoes.

4. Kitchen Exhaust Hoods

One method of indoor PM production is by high-temperature stovetop cooking. Properly venting hoods can greatly reduce production of this pollutant.¹¹¹

5. Vehicle Idling Limits

2. Fine Particulate Matter (PM2.5)

Particles with a diameter less than 2.5 µm are known as PM2.5, and are referred to as “fine” particles. These particles are believed to pose the greatest risk to human health.¹¹⁴ Fine particles primarily form from combustion processes such as coal burning, diesel emissions, gasoline combustion, power generation and other industrial processes. Additionally, some transformation products, such as sulfate and nitrate particles or secondary organic aerosols from volatile organic compound emissions, are counted as fine particles.

Figure 7 illustrates the distribution of PM2.5 air pollution worldwide in 2010. Desert areas have some of the highest concentrations of PM2.5. Large areas of rapidly industrializing countries are also subject to this type of pollution.¹¹⁵

Figure 7: Global distribution of PM2.5 pollution (Average from 2001-2006).¹¹⁵

In a landmark Harvard Medical School study analyzing PM2.5 levels from six U.S. cities between 1979 and 1988 and in the subsequent follow-up analyses, increased PM2.5 levels from mobile combustion sources (traffic) and coal combustion sources were associated with increased daily mortality rates.¹¹⁶ ¹¹⁷ Another large Harvard study conducted from 2000 to 2007 found that a 10 µg/m³ reduction in the concentration of PM2.5 was associated with an average 0.35-year increase in life expectancy in 545 U.S. counties, after controlling for demographic and socioeconomic characteristics and smoking prevalence.¹¹⁸ The New York City Department of Health estimates that each year in the city, PM2.5 pollution causes more than 3,000 premature deaths and more than 8,000 hospital admissions.¹¹⁹

The WHO indicates that the risk for various health issues has been shown to increase with exposure to PM2.5, and there seems to be no exposure threshold level at which health effects can be considered negligible.¹⁰¹ Therefore, it set limits for PM2.5 in 2005 of 25 µg/m³ for a 24-hour average period and 10 µg/m³ on average for a year (Figure 8).¹⁰¹

The EPA did not regulate PM2.5 under NAAQS until 1997 when it set limits of 65 µg/m³ averaged over a 24-hour period and 15 µg/m³ averaged over a year.¹⁰⁰ In 2006, the agency reduced the 24-hour average to 35 µg/m³, and in 2012 it reduced the annual average to 12 µg/m³ (Figure 8). Annual standards are averaged over three years, which tends to reduce the measured impact of short-term air quality events such as forest fires.¹⁰⁰

FIGURE 8: CHANGING AIR QUALITY STANDARDS FOR PARTICULATE MATTER.¹⁰⁰ ¹⁰¹

Health Effects

Respiratory System

Respiratory irritation. The EPA reports that PM2.5 causes short-term respiratory irritation, including eye, nose, throat and lung irritation, coughing, sneezing, runny nose, and shortness of breath.¹²⁰ Additionally, PM2.5 has been shown to have a deleterious effect on respiration, with statistically significant increases in hospital admissions attributed to elevated levels of PM2.5 pollution.¹²¹

Lung cancer. A study of 1.2 million adults by the American Cancer Society analyzed the relationship between air pollution, vital status, and cause of death, and demonstrated that every 10 µg/m³ increase in fine particulate matter could be associated with an approximately 8% increase in the risk of lung cancer mortality.¹²²

Respiratory-related infant mortality. A study analyzing post-neonatal deaths within five miles of a measuring station in California in 1999–2000 found an increased odds ratio of 2.13 in post-neonatal deaths from respiratory causes with each 10 µg/m³ increase in PM2.5.¹²³ A study evaluating the effect of acute exposure to particulate matter on infant mortality in Tokyo, Japan from 2002-2013 found a significant mortality risk due to exposure to PM2.5, with an odds ratio of 1.06 for infant mortality and 1.10 for postneonatal mortality with a 10 µg/m³ increase in PM2.5.¹²⁴ Notably, adverse health effects were observed even when PM2.5 levels were below Japanese air quality guidelines.¹²⁴

Cardiovascular System

Cardiopulmonary diseases. An analysis concluded that every 10 µg/m³ increase in fine particulate matter could be associated with approximately a 6% increase in the risk of cardiopulmonary mortality.¹²² In addition to chronic cardiac effects associated with PM2.5, evidence shows changes in heart rate immediately following exposure, thus increasing the risk of an acute cardiac event in people with preexisting conditions.¹²⁵

Atherosclerosis. A cross-sectional study with 798 patients investigated the association between subclinical atherosclerosis (using carotid intima-media thickness [CIMT]) and long-term exposure to PM2.5.¹²⁶ The study found that the CIMT increased by 3.9% to 4.3% with a PM2.5 exposure of 10 µg/m³. This was the first epidemiological association between air pollution and atherosclerosis.¹²⁶ The Multi-Ethnic Study of Atherosclerosis and Air Pollution, a prospective 10-year cohort study of 6795 individuals aged 45-84, furthers this evidence. Findings indicate that exposure to increased concentrations of PM2.5 was associated with progression of coronary calcification, an indication of disease acceleration.¹²⁷

Solutions

1. Vehicle Idling Limits

Cars use more fuel and cause more engine wear when they idle for more than 30 seconds compared with turning off and restarting the engine.¹¹² Heavy-duty diesel vehicles generate approximately 18,000 µg of PM2.5 per minute of idling.¹¹³ By limiting vehicle idling on nearby roads and driveways, buildings can reduce a local source of particulate matter pollution.

2. Source Reduction

In some cities and other areas, residual fuel oil, a heavier oil, is a common fuel used to provide heat and hot water in buildings. Evidence shows that fuel oil quality and type of heating system play a major role in air quality and the health of individuals living within a building and surrounding areas.¹²⁸ The consumer does often not make these choices, but local governments can regulate them.

3. Cleaner Combustion Sources

Globally, wood stoves and biomass burning are used as a primary method of heating, and it has been shown that they can have a dramatic effect on local air quality.¹²⁹ For example, in Libby, Montana, 80% of ambient PM2.5 levels were attributable to residential wood stoves. After 95% of stoves in the community were replaced with EPA-certified lower emission stoves, the average PM2.5 levels in the winter dropped by 27%. However, not all exchange programs are as successful.¹²⁹

4. Media Filtration

Filters with MERV ratings of 10 or higher will remove at least 50% of all particles of 1–3 µm, and those of 13 or higher will remove at least 90%.⁴³ A MERV 14 filter will remove at least 75% to 85% of particles of 0.3 to 1 µm.⁴³

5. Entryway Walk-Off Syste

Walk-off mats are a useful and simple means of preventing particulate matter from being carried indoors on the soles of shoes.

6. Kitchen Exhaust Hoods

One method of indoor PM production is by high-temperature stovetop cooking. Proper venting hoods can significantly reduce production of this pollutant.¹¹¹

3. Ultrafine Particles (UFPs)

Ultrafine particles are very small particles with diameters of less than 0.1 µm (100 nanometers) and are also referred to as PM0.1 or nanoparticles. They are difficult to characterize, as air concentrations are highly dependent on the proximity to sources such as high-volume traffic. Unlike PM10 and PM2.5, UFPs are typically measured using particle counts per unit of volume (e.g., ppm) rather than mass per unit of volume (e.g., 10 µm/m³). They have a much higher count-to-mass ratio and consequently a nearly negligible mass compared with larger airborne particles. Their small size means it is possible though not always likely for them to be drawn deep into the lungs, maximizing their damage (Figure 10). UFPs are currently unregulated and have high spatial and temporal variability.¹³⁰

UFPs are responsible for some of the health effects caused by PM2.5 and PM10 due to the fact they often make up a portion of the particulate mix.¹³¹ Generally, exposure to UFPs is generally not a homogenous event, and the toxic effects of UFPs can be significantly enhanced by the presence of other pollutants as well as small differences in chemistry, size, and solubility.¹³²

Health Effects

Respiratory System

Respiratory inflammation. A 2003 study comparing the ability of coarse, fine, and ultrafine particles to cause oxidative stress, a precursor to pulmonary inflammation, found that UFPs demonstrated increased biological potency by inducing structural damage in the mitochondrial region.¹³³ Additionally, their chemical composition included a high amount of reactive oxygen species, a further indication that UFPs induce oxidative stress.¹³³

Peak expiratory flow. A study evaluating the effects of a particulate matter mix on a group of nonsmoking, asthmatic adults found a greater decrease in the subjects’ peak expiratory flow when the portion of UFPs in the mix was larger.¹³⁴ The authors concluded that respiratory effects are positively associated with the number of ultrafine particles in ambient air.¹³⁴ Additionally, a 2008 study of cyclists with short-term exposure to UFP’s found significant associations between increased levels of UFP concentrations and reduced lung function.¹³⁵

Heart Disease. An analysis of more than 100,000 teachers in the state of California over the course of six years showed that not only is exposure to UFP significantly associated with ischemic heart disease (IHD) but that it is highly dependent upon the elemental makeup of the UFPs.¹³⁶ The study showed that the fraction of UFPs with the greatest association to IHD comes from mobile source emissions (e.g., diesel and gasoline).¹³⁶

Solutions

1. Kitchen Exhaust Hoods

One method of indoor PM production is by high-temperature stovetop cooking. Proper venting hoods can greatly reduce production of this pollutant.¹¹¹

2. Vehicle Idling Limits

Cars use more fuel and cause more engine wear when they idle for more than 30 seconds compared with turning off and restarting.¹¹² Since vehicle emissions are the major source of ultrafine particles in most cities, limiting idling near buildings can help reduce local concentrations.¹³⁰

Specific Airborne Particles and Fibers

The presence of tiny solid particles in inhaled air is often sufficient to cause damage to the respiratory and circulatory systems. However, particulate matter becomes inherently more dangerous with the presence of chemicals such as diesel exhaust, lead, mercury, or asbestos.

1. Diesel Exhaust Particulate Matter

Due to incomplete combustion processes, the exhaust of diesel engines contains various gases, liquids, and solid particles composed of elemental carbon with sulfates, metals, and other substances.¹³⁷ Diesel exhaust particulate matter (DEP) created by trucks, boats, farm equipment, and generators can cause adverse health effects, such as coughing and nausea (especially in children) and short-term irritation of the eyes and throat.¹³⁷

Some of the pollutants associated with diesel exhaust, specifically sulfur oxides, are becoming less of a concern as diesel fuel is becoming cleaner. The EPA’s 2006–2010 phase-in for ultralow sulfur diesel fuel is estimated to decrease exhaust emissions by 90%.¹³⁸

Although DEP is not directly part of NAAQS, some of the constituents of DEP are. The EPA recommends an outdoor diesel exhaust concentration, which includes DEP, of less than 5 µg/m³ (one-third of the NAAQS PM2.5 limit), which is set as a reference concentration intended to protect against non-carcinogenic health effects.¹³⁷

Health Effects

Respiratory System

Allergic sensitization. In a study of ragweed-sensitive subjects, diesel particulates were shown to potentiate the production of immunoglobulin-E (IgE), a class of antibodies known to play a crucial role in hypersensitivity ¹³⁹. This correlation suggests that diesel particulate matter increases sensitization to allergens.¹³⁹

Allergic asthma. In an allergy challenge study researching the effects of DEP on allergic asthma, researchers exposed mice to 100 µg of DEP intratracheally for six weeks, as well as to an antigen (ovalbumin), or to a vehicle only or an antigen only. The antigen-induced accelerated airway inflammation and increased the number of goblet cells in airways and the local expression of Th2 cytokines in the mice also exposed to DEP. The authors concluded, “These results provide the first experimental evidence that DEP can enhance the manifestations of allergic asthma”.¹⁴⁰ Additionally, research on inner-city children shows that when pollution elements are individually assessed, it is the carbonaceous soot from diesel exhaust that is most highly correlated with the exacerbation of existing asthma.¹⁴¹

Immune function. In a study on the effects of DEP on immune function, researchers exposed rats to extremely high levels of DEP, either 50 or 100 mg/m³, or to purified air (exposure to this level of DEP is unlikely for humans in normal settings).¹⁴² Two hours after the exposure, the rats were exposed to the bacterium Listeria monocytogenes. The researchers found that in rats exposed to DEP, phagocytosis and Listeria-induced basal secretion of interleukin-1β (IL-1β) and IL-12 by alveolar macrophages was suppressed in a dose-dependent manner. The authors concluded that DEP retards bacterial clearance from the lungs, weakens innate immunity and may suppress cell-mediated immunity, thus increasing the susceptibility to bacterial infection.¹⁴² Additionally, a study exploring the impact of exposure to DEP extracts on human macrophages (key players in the human immune response) found that DEP exposure may alter expression of certain essential macrophage functions, potentially resulting in deleterious immune effects.¹⁴³

Respiratory and Endocrine Systems

Lung Cancer. In 2012, WHO’s International Agency for Research on Cancer (IARC) classified diesel exhaust as a known (Group 1) human carcinogen.¹⁴⁴ In an effort to further explore the mechanisms of carcinogenicity, an analysis from the Health Effects Institute (HEI), concluded that “the small respirable soot particles in diesel exhaust are primarily responsible for lung cancer developing in rats exposed to high concentrations of diesel emissions”.¹⁴⁵ However, more research is needed regarding the mechanisms and the particle concentrations and duration of exposure that lead to lung cancer and before these findings can be extrapolated to humans.¹⁴⁵

Solutions

1. Vehicle Idling Limits

Avoiding motor vehicle idling, including cars with diesel engines, can minimize the risk of diesel exhaust particles.¹³⁷

2. Media Filtration

Diesel exhaust particulates are composed of fine (PM2.5) and ultrafine (PM0.1) particulate matter.¹³⁷ Filters with MERV ratings of 10 or higher will remove at least 50% of all particles of one to three µm, and those of 13 or higher will remove at least 90%. A MERV 14 filter will remove at least 75% to 85% of particles of 0.3 to 1 µm.⁴³

2. Lead Particulates

Lead is a corrosion-resistant, dense and malleable blue-grey metal. It has been used for much of human history for various building applications. Lead sheets are used as architectural metals in roofing, flashing, gutters, gutter joints, and roof parapets. Until it was banned in 1977, lead-based paint was commonly used in homes and other buildings. Lead pipes were used for connecting buildings to water mains and declined in use after 1930.¹⁴⁶ Existing lead in the environment is an ongoing health issue.¹⁴⁷ Mining, smelting, and refining activities also result in significantly increased levels of lead in the environment.¹⁴⁷

Lead is a potent toxicant that can affect most systems and organs in the body.¹⁴⁸ Young children are particularly vulnerable to lead poisoning, which can result in learning problems, lower IQ, slowed growth, hearing problems, anemia, and other issues. In adults, lead exposure can lead to constipation, nausea, irritability, headache, forgetfulness, and depression.¹⁴⁸

Lead becomes inhalable once it is burned or melted and released as a fume, and this route of exposure generally affects occupational workers. Lead may also be inhaled when dust that contains lead becomes airborne. Airborne lead particles in outdoor air can also be tracked into the indoor environment through foot traffic or as dust.¹² In response to the hazards and pervasive nature of lead, the original NAAQS limit for lead, 1.5 µg/m³, was reduced by the EPA in 2008 to 0.15 µg/m³ for a rolling three-month average.¹⁰⁰ The CDC and OSHA have also set an eight-hour average indoor air maximum concentration for lead at 50 µg/m³. Despite such efforts, as recently as 2011, the CDC confirmed that as many as 535,000 children have high lead blood levels.¹⁴⁹ ¹⁵⁰

Lead was used in gasoline in the U.S. until 1988 (except for Alaska, where it was used until 1991) and was officially banned from use in gasoline in 1995.¹⁵¹ Apart from exposure through food, water, and soil, atmospheric lead is a major source of pollution. Exposure to airborne lead can occur through inhalation of combustion products, including waste, coal, oil, and tobacco, as well as emissions from metal manufacturing and lead smelting.

The phase-out of leaded gasoline has however greatly reduced ambient lead levels. Between 1980 and 2007, average ambient concentrations in the U.S. decreased by almost 94%.¹⁵² In 2002, average ambient lead concentrations were less than 0.05 µg/m³.¹⁵³

Communities living near smelting sites are especially at risk to high blood lead levels. A study measuring blood levels in 781 children living near a lead smelter in northern Idaho concluded that ambient air lead exposure was the strongest individual factor that influenced lead blood levels, and it explained 55% of the occurring variances in lead blood levels.¹⁵⁴

For more on the effects of lead and ways to avoid exposure, refer to the Water WELLography™ and Materials WELLography™.

Health Effects

Nervous System

Health Hazard. Although lead accumulates in bone marrow, the nervous system is the main target for toxicity. In 2001, the Missouri Department of Health and Senior Services and the Jefferson County Health Department conducted blood lead screening of a community in Herculaneum, Missouri, near a lead-processing plant.¹⁵⁵ The 52-acre facility, an active processing plant that smelts lead ore (80% lead sulfide), sits adjacent to residential neighborhoods to the north, south, and west. 935 people were screened, of which 655 were adults aged 18 or older. Results indicated that 28% of children in the community had lead poisoning, or had blood levels known to cause harmful health effects, at 10 µg/dL or higher. Given the known effects associated with lead levels of 10 µg/dL, the CDC has lowered the reference level of lead in blood for children to 5 µg/dL.¹⁵⁵ The average blood lead level in young American children, according to data from the National Health and Nutrition Examination Survey (NHANES), conducted by the CDC between 1996 and 1999, is 2 µg/dL.¹⁵⁶

Impaired cognitive development. Children under the age of seven are especially at risk for exposure, as even low blood levels can result in a deficit in cognitive development.¹⁵⁷ There is no known safe level of lead exposure for children. Exposure often causes no obvious symptoms but has been linked to loss of cognition, shortened attention span, altered behavior, dyslexia, attention deficit disorder.¹⁵⁸ Research suggests a neuropsychological manifestation due to low-doses exposure during childhood affects the function of a child’s central nervous system, even after the ingestion of lead has declined or stopped.¹⁵⁹ Furthermore, lead exposure is cumulative. Thus, low levels can cause cognitive decline if the exposure takes place over long periods of time.¹⁶⁰

Solutions

1. Pollutant Restriction and Abatement

All surface materials in buildings should contain no more than 100 ppm by weight of added lead. For buildings constructed before 1978, lead evaluation and abatement should be done in accordance with the EPA guidelines.¹⁶¹

2. Air Filters

Air filters with MERV ratings of 10 or higher will remove at least 50% of all particles of one to three µm, filters at MERV 13 or higher will remove at least 90% of particulates along the same range.⁴³ A MERV 14 filter will remove at least 75% to 85% of particles 0.3 to one µm.⁴³

3. Mercury Particles

Mercury exists in three forms: elemental, inorganic, and organic. All forms are toxic, although to different extents and with different effects.¹⁶² It is released into the air when wood, coal, gas, or waste containing mercury is burned and can move far from its initial source through the atmosphere.

Elemental mercury is or has been used in thermometers, barometers, and pressure-sensing devices as well as batteries, fluorescent lights, thermostats, industrial processes, refining, and lubrication oils.¹⁶³ Inorganic mercury was mostly used in the past in skin-lightening creams and soaps and latex paint. Many of those uses have been ended or reduced in the U.S. For example, mercury is no longer used in paint, and most batteries are also made without mercury.¹⁶⁴ ¹⁶⁵ ¹⁶⁶ The majority of emissions of mercury are from the combustion of fossil fuels and waste.¹⁶⁷ While agricultural and pharmaceutical uses of inorganic mercury have mostly ceased in the U.S., mercuric chloride is still used as a disinfectant and pesticide.

For more information on mercury, refer to the Materials WELLography™.

Health Effects

Urinary System

Kidney disease. The WHO reports that inhalation of mercury vapor may produce harmful effects on the kidneys, including increased protein in the urine and kidney failure.¹⁶⁸ More specifically, a study in Runcorn, England, which had been the site of high industrial activity for more than 100 years, found a significant exposure-response relation between modeled estimates of mercury exposure and risk of death from kidney disease.¹⁶⁹ The authors suggested that long-term, low-level exposure to the mercury-bearing exhausts of the nearby chlor-alkali process plant and coal-fired power station may be associated with excess kidney disease mortality in the population.¹⁶⁹

Nervous System

Developmental disabilities. A comparison of administrative data from the Texas Education Agency and data regarding environmentally released mercury from the EPA’s Toxics Release Inventory found an association between environmentally released mercury and developmental disabilities at a county level mercury.¹⁷⁰ On average, the rate of special education services increased by 43% and the rate of autism increased by 61% for every 1,000 pounds of environmentally released mercury.¹⁷⁰ Inhalation of mercury vapor among children is also associated with disturbances in the central nervous system, such as tremor and coordination difficulties, as well as mercurial erethism, which includes symptoms such as excitability, loss of memory, insomnia, and extreme shyness.¹⁷¹

Solutions

1. Media Filtration

Atmospheric particulate mercury tends to be between one and six µm in diameter.¹⁷² Filters with MERV ratings of 10 or higher will remove at least 50% of all particles of one to three µm, and those of 13 or higher will remove at least 90%. Filters with MERV ratings of eight or higher will remove at least 70% of all particles of three to 10 µm, and those of 12 or higher will remove at least 90%.⁴³

4. Asbestos Fibers

A naturally occurring mineral comprised mostly of fibrous silica, asbestos has been mined and used for thousands of years.¹⁷³ It is malleable and chemically inert, has high electrical and thermal resistance, and has been used in insulation, as a fireproofing material, in automobile brakes, and in many other products.

The U.S. has phased out most uses of asbestos,¹⁷³ whereas the European Union forbids the manufacture or import of any products that contain asbestos.¹⁷⁴

When asbestos-bearing sheetrock or building materials are disturbed during a renovation, asbestos fibers are released into the air.¹⁷³ The most common pathway into the human body is through inhalation. Inhaled asbestos fibers can lead to lung cancer and lung scarring. The fibers can become lodged in the lungs and over the course of several years scar the lungs, resulting in chronic coughing and shortness of breath. This condition, known as asbestosis, is untreatable. As with radon exposure, the risk is compounded for individuals who smoke.¹⁷³ Workplace exposure to asbestos is also linked to cancer of the larynx, ovaries, and other organs.¹⁷³

Detailed health effects, as well as solutions on how to prevent exposure to asbestos, are included in the Materials WELLography™.

Gases

There are a wide variety of potentially toxic gases present throughout our environment, which come from multiple sources. Below are some of the most commonly encountered gases.

1. Cardion Dioxide

Most living organisms, including humans, exhale CO2 through respiration.¹⁷⁵ Without sufficient ventilation, CO2 would continuously accumulate in occupied buildings. It is easy to detect, so it is often used as an indicator of occupancy when monitoring and adjusting ventilation systems. Although it is not harmful at commonly experienced concentrations, high CO2 levels may be linked to the presence of odors and other volatile organic compounds from improperly tuned ventilation systems.¹⁷⁵

The EPA notes that indoor concentrations of 1,000 ppm (0.1%) for continuous exposure indoors are indicative of lack of proper ventilation ¹⁷⁶ and the National Institute for Occupational Safety and Health (NIOSH) and OSHA recommend 5,000 ppm as an eight-hour time-weighted average.¹⁰² The Illinois Department of Public Health recommend floor-wide averages of 800 ppm or less.¹⁷⁷

Health Effects

Nervous System

Impaired decision-making. New evidence suggests a link between CO2 exposure and impaired decision-making.¹⁷⁸ A 2012 study exposed participants to three different CO2 levels in an otherwise unchanged office-like room for two and a half hours at a time and asked them to complete nine decision-making tests and questionnaires. Relative to the lowest level of CO2 exposure of 600 ppm, moderate but statistically significant reductions in performance were seen at 1,000 ppm. At 2,500 ppm, large statistically significant reductions in performance were observed (Figure 9). The authors suggested that CO2 may not only be an indicator of the presence of other air pollutants but by itself may affect the decision-making processes at levels considered not threatening to human health.¹⁷⁸

Headaches. At 4,000 ppm, a level roughly 10 times that found in the atmosphere, carbondioxide can cause headaches.¹⁷⁹

FIGURE 9: CARBON DIOXIDE LEVELS AND DECISION-MAKING.¹⁷⁸

Solutions

1. Adequate Ventilation Rates

ASHRAE recommends ventilation rates based on occupancy for a variety of spaces in its Standard 62.1, Ventilation for Acceptable Indoor Air Quality in Table 6.2.2.1.¹⁸⁰ Exact rates differ by use type, but for most spaces with stationary activities, they range from five to 10 cfm/person, or 0.06 to 0.12 cfm/ft².¹⁸⁰ Other standards also specify recommended ventilation rates in buildings, such as EN 15251, AS 1668.2, CIBSE Design Guide A, and others.

ASHRAE standards also allow buildings to vary their ventilation rates depending on changing occupancy levels. These demand-controlled ventilation systems can respond directly to CO2 levels, or to occupancy sensors or schedules.¹⁸⁰

2. Operable Windows

Windows that can be opened by the people within the building or automated systems can rapidly increase the amount of outside air entering a building. While this is effective at reducing carbon dioxide levels, care must be taken to avoid introducing air that is high in other pollutants, such as ozone and particulate matter.¹¹⁰

2. Carbon Monoxide

Carbon Monoxide (CO) is a colorless, odorless, and tasteless gas that is slightly lighter than air. It results from the partial oxidation of carbon when there is not enough oxygen available to form CO2.¹⁸¹ CO also occurs in small quantities during normal animal metabolism. While carbon monoxide does not usually present a problem outside (except in high traffic or automobile tunnels), in indoor spaces with inadequate ventilation, the gas can accumulate more easily. Therefore, ventilation is important, especially in rooms that contain CO sources, such as garages, kitchens with gas stoves, and rooms with gas clothes dryers. Just two minutes of operating a car in a garage, even with the garage door open, can increase the CO level to 500 ppm, which is 55 times above the acceptable limit set in the EPA’s NAAQS.¹⁸¹

CO has 210 times the binding affinity to hemoglobin of O2, and therefore it blocks oxygen binding and prevents the oxygen from being carried throughout the body.¹⁸² The lack of O2 being delivered causes a condition known as hypoxia. Hypoxia can cause nausea, fatigue, and death. Pregnant women and smokers are at higher risk of severe health effects due to CO since they already have compromised O2 delivery mechanisms.¹⁸²

FIGURE 10: HEMOGLOBIN AND GASEOUS EXCHANGE.¹⁸²

Every year in the U.S. unintentional CO poisoning (not linked to fires) results in 20,000 visits to the emergency room, more than 4,000 hospitalizations, and approximately 400 deaths.¹⁸³ Carbon monoxide poisoning is associated with a variety of nonspecific symptoms. At levels twice the personal exposure limit (PEL) of 35 ppm some people may experience headaches, fatigue, and nausea.¹⁸⁴ Between 10-40,000 Americans miss work or seek medical attention each year due to CO exposure,¹⁸⁵ and 170 people die per year from CO poisoning in the U.S., excluding deaths related to automobile emissions.¹⁸⁶

The EPA requires all U.S. localities to maintain outdoor CO concentration below a nine-ppm average for any eight-hour period and 35 ppm for any one-peak hour, and all counties currently adhere to this regulation.¹⁸⁷ ¹⁸⁸ The WHO also recommends limiting exposure based on time: 90 ppm for 15 minutes and 10 ppm for an eight-hour exposure.¹⁸⁹ For occupational safety, OSHA initially recommended 50 ppm as a transitional time-weighted average over eight hours, and NIOSH set the final recommendation at 35 ppm.¹⁹⁰

Health Effects

Cardiovascular System

Cardiovascular disease mortality. A study analyzed the cardiovascular health of 5,529 tunnel officers employed by the Triborough Bridge and Tunnel Authority in New York City between 1952 and 1981, who were exposed to increased CO levels.¹⁹¹ CO measurements varied between 35 ppm and 300 ppm, with peaks during rush hour, until ventilation was increased in 1970. Compared to the New York City population, as well as to unexposed bridge officers with similar backgrounds and age, the tunnel officers had a 35% higher risk of arteriosclerotic heart disease mortality.¹⁹¹

A study of 19 European Union cities found a 1.25% increase in cardiovascular deaths associated with a 0.87 ppm (one mg/m³) increase in the two-day average CO levels.¹⁹²

Nervous System

Delayed neuropsychological sequelae (DNS). DNS usually occurs some weeks after severe CO poisoning and involves a-specific symptoms, such as a variety of neurological deficits, including cognitive and affective problems. In a retrospective study examining medical records of all admitted CO-poisoned patients in the emergency department of Care University General Hospital in Florence, Italy, between 1992 and 2007, 24.1% of the 141 patients participating in the follow-ups were diagnosed with DNS a month after their initial release from the hospital.¹⁹³ Similarly, a study of 100 patients experiencing acute CO poisoning found that 20% developed DNS, with poorer outcomes associated with older age as well as those who experienced earlier onset post-poisoning.¹⁹⁴

Headache. The CDC notes that headaches are one of the most common symptoms of CO exposure.¹⁹⁵ A study involving 100 patients who had been diagnosed with acute CO poisoning investigated the subjects’ headache symptoms in order to develop a better diagnostic protocol for CO poisoning. The headaches described varied—ranging from dull to sharp, continuous to intermittent, or throbbing, and no typical characteristic of a CO-induced headache could be defined.¹⁹⁶

Solutions

1. Kitchen Exhaust Hoods

Carbon monoxide is an odorless colorless gas produced by space heaters, gas stovetops, and ovens. Venting hoods over the stove can greatly reduce this pollution.¹¹¹

2. Vehicle Idling Limits

Cars use more fuel and cause more engine wear when they idle for more than 30 seconds compared with turning off and restarting the engine.¹¹² Cars and trucks that use gas generate approximately 1.2 g CO per minute and heavy-duty diesel vehicles generate 0.43 g/min CO per minute of idling.¹¹³ By limiting vehicle idling on nearby roads and driveways, buildings can reduce a local source of particulate matter pollution.

3. Ozone

Ozone (O3) is a reactive oxygen molecule that can impact our health. According to the EPA, ozone can trigger a wide variety of effects, including chest pain, coughing, throat irritation, and congestion, and can worsen asthma, emphysema, and bronchitis.¹⁹⁷

Ozone is most often formed by a reaction in the atmosphere between solar radiation (sunlight) and oxygen. It can also be generated indoors by copy machines, high voltage electronics, and specific ozone generators used in air purifications. Ground-level ozone, the type that affects humans, is created when pollutants from cars, power plants, boilers, chemical plants, and other sources react with sunlight.¹⁹⁷ Ozone enters buildings through ventilation systems, particularly when ozone levels are high, like on hot sunny days.

The photochemical processes involved in the formation of ozone are relatively well documented and can be summed up as the chain reaction initiated by sunlight creating water vapor and singlet oxygen (O1) (Figure 11).¹⁹⁸ Since singlet oxygen is not stable in the atmosphere, it quickly binds with available oxygen (O2) to form ozone (O3).

Ozone naturally occurs as a layer in the earth’s upper atmosphere (stratosphere) and provides a crucial service necessary for life on earth by filtering out ultraviolet light (radiation). Ozone generated at ground level is chemically the same as upper atmospheric ozone (O3). However, due to health effects associated with direct inhalation exposure, it is a negative air pollutant with no beneficial effect like its upper atmospheric counterpart.¹⁹⁸

FIGURE 11: PHOTOCHEMICAL FORMATION OF OZONE.¹⁹⁹

The EPA recently reduced the limit on ambient outdoor ozone levels to 75 ppb from 80 ppb, averaged over eight hours (the EPA considers a region noncompliant if the fourth highest measurement of the year exceeds restriction).²⁰⁰ However, the Clean Air Scientific Advisory Committee (CASAC) of the EPA recommends setting a standard between 60 and 70 ppb and does not believe the 75-ppb limit to be sufficiently protective.²⁰⁰

OSHA guidelines in the workplace are based on time-weighted averages and are limited to 100 ppb for eight hours of exposure per day while doing light work.²⁰¹ According to NIOSH, ozone levels of five ppm (5,000 ppb) or higher are considered immediately dangerous to life or health. The NIOSH recommended exposure limit for ozone, consistent with OSHA, is 100 ppb.²⁰¹

Several hundred counties in the U.S. exceed the EPA’s limit of 75 ppb, with only a few rural counties measuring ozone levels of 60 ppb, and almost no region in the country meets WHO’s 51-ppb limit.²⁰² If all locations in the U.S. could meet the new standard of 75 ppb, the EPA estimates that as many as 2,300 fewer deaths and 43,000 fewer lost workdays would be accumulated over the next half-decade. If the outdoor air standards were set at a more stringent level of 65 ppb, the EPA believes the cleaner air would prevent up to 7,100 deaths and 110,000 lost workdays.²⁰²

FIGURE 12: DEVELOPMENT OF OZONE STANDARDS.¹⁰⁰ ¹⁰¹

Health Effects

Respiratory System

Respiratory diseases. Ozone found at ground level is highly toxic, and exposure can result in triggering asthmatic events and lung damage.²⁰³ ²⁰⁴

A study in 16 Canadian cities counted a total of 720,519 hospital admissions due to respiratory diseases from 1981 to 1991.²⁰⁵ After controlling for covariates and other air pollutants (SO2, NO2, CO), the study found an association between ozone levels recorded one day before admission and the number of admissions (relative risks varying among cities between 1.0 and 1.088) from April to December. The authors suggest that relatively low ambient ozone levels lead to excess hospital admissions for respiratory diseases.²⁰⁵ Additional research has found that among healthy individuals there is no uniform response pattern, but airway responses, epithelium permeability, and forced expiratory volume were all significantly altered among different sub groups, indicating an array of possible negative outcomes.²⁰⁶

Respiratory mortality. A 2009 epidemiological study analyzed nearly half a million people living in almost 100 metropolitan statistical areas across the lower 48 states of the U.S.²⁰⁷ The authors found that increased concentrations of O3 corresponded to higher rates of respiratory mortality, independent of other pollutants. A 10 ppb increase in ambient levels was associated with a 4% increase in the risk of death.²⁰⁷

Respiratory System

Asthma. The EPA states that long-term exposure to ozone is not only linked to aggravation of pre-existing asthma, but it also likely one of the causes of asthma development.²⁰⁸ Children in particular are most at risk as their lungs are still developing and they are most likely to be outdoors when ozone levels are high.²⁰⁸ A cohort study followed 3,535 children in various communities in Southern California for five years, and 265 of the subjects were diagnosed with asthma.²⁰⁹ In children playing three or more sports in communities with high ozone levels, the relative risk of developing asthma was 3.3 times that of children playing no sports. Spending time outside in these areas was likewise positively associated with asthma (relative risk of 1.4), whereas playing sports in areas with low ozone levels was not (relative risk of 0.8).²⁰⁹

Solutions

1. Carbon Air Filtration

Carbon filters can remove 60% to 70% of ozone from the passing air, according to a test performed in Sacramento, California, by Lawrence Berkeley National Laboratory.²¹⁰

4. Nitrogen Dioxide

Exposure to nitrogen dioxide (NO2) can lead to respiratory effects including airway inflammation and increased symptoms in people with asthma.²¹¹ NO2 is a product of combustion and is mainly found near burning sources such as wood smoke and traffic combustion. The air in many indoor spaces has half the amount of NO2 as outdoor air. However, indoor areas containing gas stoves, fireplaces and cigarette smoke often have a high concentration of NO2 and require monitoring and good ventilation in order to be safe. Nitrogen dioxide and nitrogen oxide (NO), often formed simultaneously during combustion processes, are collectively classified as NOX.²¹¹

NO2 can be detected by smell at 100 to 400 ppb, or 0.4 ppm. Exposure to 150 ppm (150,000 ppb) or more of NO2 can cause death from pulmonary edema,²¹² and exposure of 174 ppm for one hour has been associated with a 50% chance of mortality.²¹³ Animals exposed to one ppm (1,000 ppb) of NO2 for several months show signs of chronic health issues.

EPA and ASHRAE’s annual limit for outdoor NO2 concentration is 53 ppb, with hourly peaks of less than 100 ppb ²¹⁴. WHO’s annual guideline for NO2 is 40 µg/m³, with hourly peaks below 200 µg/m³ ¹⁰¹.

Health Effects

Respiratory System

Respiratory irritation. The EPA reports that the effects of NO2 are similar to allergens and can lead to cold-like symptoms and trigger asthmatic events when inhaled.²¹⁴ NO2 also causes eye irritation and dryness of the nose and throat.²¹⁴

Respiratory mortality. In the past, NO2 exposures have frequently occurred in crop storages in farm silos, where toxic levels of nitrogen are often produced after the silos are filled with an organic material.²¹⁵ “Silo filler’s disease” is a well-known example of the morbidity and mortality associated with NO2 exposure, leading to symptoms such as respiratory tract irritation, bronchiolitis obliterans, pulmonary edema, and death.²¹⁵

Upper respiratory symptoms. The EPA notes that breathing in air with high concentrations of NO2 can irritate the human respiratory system and aggravate respiratory diseases (such as asthma), leading to adverse respiratory symptoms, hospital admissions, and emergency room visits.²¹⁶ A study analyzing the upper respiratory health of 1,854 schoolchildren (aged nine to 11 years old) found a significant association (odds ratio of 1.82) between upper respiratory illnesses, such as a running nose, a cough or hoarseness, and exposure to moderate levels of NOX (maximum concentrations ranging between 49–502 µg/m³).²¹⁷

Respiratory and Immune Systems

Asthma. A three-year cohort study carried out in seven communities in Japan determined an average NO2 pollution for each community and assessed the respiratory symptoms of 842 schoolchildren via questionnaires.²¹⁸ A 10 ppb increase in outdoor NO2 was associated with a 76% increase in the incidence of wheezing, and a 210% increase in the incidence of asthma (odds ratio of 1.76 and 2.10, respectively).²¹⁸ Several studies have shown that children are likely affected by the use of gas stoves in the home and that emissions from them are likely triggers for asthma. While this link has been shown in children, it has not been verified to the same degree in adults.²¹⁹

Cardiovascular System

Cardiopulmonary mortality. A 2006 study suggested an association between elevated NO2 exposure and a 57% higher risk of cardiopulmonary mortality, after adjusting for socioeconomic factors and smoking.²²⁰

Solutions

1. Vehicle Idling Limits

Cars use more fuel and cause more engine wear when they idle for more than 30 seconds compared with turning off and restarting the engine.¹¹² Cars and trucks that use gas generate approximately 60,000 µg and heavy-duty diesel vehicles generate 560,000 µg of nitrous oxides per minute of idling.¹¹³ By limiting vehicle idling on nearby roads and driveways, buildings can reduce a local source of particulate matter pollution.

2. Operable Windows

Windows that can be opened and closed by the people in the building or automated systems can rapidly increase or decrease the amount of outside air entering a building, depending on the outdoor air conditions. This combined with filtration or air conditioning is effective at reducing ozone and NO2 levels.¹¹⁰

3. Kitchen Exhaust Hoods

Gas stovetops and ovens produce nitrogen dioxide. Venting hoods over the stove can greatly reduce this pollution.¹¹¹

5. Radon

Radon is a naturally occurring gas that results from the radioactive breakdown of uranium (Figure 13). The primary health risk from radon exposure is lung cancer.²²¹

Radon is odorless, colorless and tasteless, and enters working and living spaces through cracks in building foundations.²²² The gas can accumulate in buildings, especially in confined areas such as attics and most commonly, basements. It leaves the surrounding soil and enters basements because of a slight pressure difference driven by buoyant natural circulation that results from temperature differences indoors. Water from deep wells drilled into rock may contain high radon levels, and homes that draw water from such sources may introduce radon through the plumbing.²²²

FIGURE 13: RELATIVE HALF-LIFE OF PRODUCTS FROM URANIUM DECAY.²²³

Radon is a radionuclide that decays through short-lived progeny (radon daughters) before eventually reaching its stable end product, lead.²²⁴ Throughout the decay process, radon and its products emit ionizing particles that attach to particulate matter in the air. As radon decays into polonium, it releases atomic particles made up of two protons and two neutrons. These “alpha” particles are ionizing but are blocked by most matter, such as the thin layer of dead cells, which make up the outermost layer of skin. Nevertheless, if radon gas is inhaled, the alpha particles will directly impact the lung cells and potentially cause mutations.²²⁴

Radon’s radioactive by-products tend to attach to particulate matter such as elemental carbon. These particles are then carried and deposited in the lungs. Thus, in buildings with a higher concentration of indoor particulate matter or for those who smoke, radon poses a larger threat.²²⁵

The International Standard (SI) unit of measure for radioactivity is the Becquerel (Bq) and in the U.S., the more commonly used unit is the Curie (Ci).²²⁶ One Bq corresponds to the transformation (disintegration) of one atomic nucleus per second, which is equal to 2.7 x 10(^-11) Ci (0.27 pico curie, or pCi). Average indoor U.S. radon levels are estimated to be 1.3 pCi/L, and outdoor air carries about 0.4 pCi/L. The EPA suggests homeowners with radon levels above four pCi/L to take steps to reduce the levels in their homes, with some individual states in the U.S. requiring radon abatement in homes prior to sale ²²⁶. Radon in water typically adds one pCi/L to the indoor air levels for every 10,000 pCi/L in water.²²⁷

FIGURE 14: RADON AND PREVENTABLE DEATHS IN THE UNITED STATES.²²⁶

Health Effects

Respiratory and Endocrine Systems

Lung cancer. Among nonsmokers, indoor exposure to radon is the leading cause of lung cancer and the second overall leading cause of lung cancer.²²⁹ Radon is responsible for about 21,000 deaths per year in the U.S.²²⁹

A 2006 study analyzed data from seven North American case-control studies using long-term α-track detectors to assess residential exposures to radon and to investigate a possible association with an elevated risk of lung cancer.²³⁰ An 11% increase in odds (odds ratio of 1.11) was estimated after exposure to radon at a concentration of 100 Bq/m³ (2702 pCi/L) in the exposure timeframe of five to 30 years. Reducing the data to a subset with higher precision regarding the radon exposure led to a further increase in risk. This was one of the first studies to provide direct evidence on the correlation between radon exposure and elevated risk of lung cancer outside of the occupational setting of mining, which has higher exposure dosages.²³⁰

Solutions

1. Adequate Ventilation

In its Consumer’s Guide to Radon Reduction, the EPA recommends increased ventilation of spaces to reduce radon levels.²³¹ This can be achieved through passive ventilation (e.g., by installing additional vents) or by temporarily opening windows, as well as through active ventilation using fans to expedite air exchange. Heat recovery ventilators (HRVs), which are especially effective in removing radon from basements, use the expelled indoor air to heat or cool the introduced outdoor air, maintaining a comfortable indoor environment.²³¹

2. Sealing of Radon Entry Routes

In addition to increasing ventilation, the EPA recommends sealing cracks in basements and foundations, through which radon may enter the home. This solution makes ventilation techniques more efficient and saves energy.²³¹

Volatile Organic Compounds (VOCs)

Unlike ozone and nitrogen oxides, which mainly form in outdoor areas, some VOCs arise from newly installed products or activities within buildings. Materials used for ongoing maintenance, such as cleaning products, air fresheners, pest control chemicals, and furniture polish can increase VOC levels for a period of time, and their presence indoors is commonly two to five times higher than outdoor levels.¹⁰ Furthermore, human occupancy is responsible for the generation of VOCs from odors, personal care products, perfumes, shoe polish, hair spray, and electronic devices. However, not all VOCs or levels of exposure are anthropogenic or harmful.¹⁰

Semi-Volatile Organic Compounds, or SVOCs, are a subcategory of VOCs that have a boiling temperature above that of water (between 240°C and 400 °C).²³² Nevertheless, SVOCs can vaporize from products, as they are not bound to the materials and can become distributed throughout the indoor environment. SVOCs are present at very low levels in some commercial products, such as plasticizers in flooring, pesticides, and flame-retardants in insulation, and many have known toxicological effects at levels of exposure significantly higher than those generally experienced in buildings.²³²

According to the EPA, the health effects of high levels of exposure to some VOCs can include eye, nose, and throat irritation, headaches, loss of coordination, nausea, and damage to the liver, kidney, and central nervous system.¹⁰

New furniture and newly installed building materials—including specifically composite wood products—can be the largest source of harmful indoor VOCs that decline with time and use.²³³ While individual sources may have low VOC emissions, the cumulative effects of multiple products and materials used inside a home or building can elevate concentrations. It is important to understand the total level of VOC exposure over time given that many products labeled “low VOC” can be found in combination with other products.²³³

Central nervous system effects (e.g., dizziness) may be an early indication of VOC exposure, as the brain is believed to be an easy target due to its high lipid content and steady supply of blood, especially given that VOCs are known to be able to permeate lipid membranes.¹⁵ Sick building syndrome (SBS) is used to describe acute health affects linked to building occupancy but without a specific diagnosis of a disease or a directly identified cause.¹⁵ SBS is most frequently attributed to poor ventilation and has also been associated with off-gassing by some newly installed building materials and furnishings.¹⁵ A study involving 12 California buildings found an association between VOC exposure metrics and SBS symptoms.²³⁴ One of the seven VOC-based metrics tested, the “irritancy/principal components” metric, was a statistically significant predictor of general symptoms (i.e., eye, nose, throat, and skin irritation). The irritant symptoms were found to be associated with carpet VOC emissions (styrene) and cleaning products (2-butoxyethanol and 2-propanol).²³⁴

In combination with indoor or outdoor NO2 and sunlight, VOCs react to produce ozone.¹⁰¹ They can also react with nitrogen oxides or O3 to produce new substances and secondary aerosols, which have been shown to cause sensory irritation symptoms.²³⁵ Few regulatory agencies have limits for VOC concentrations in the air and instead limit emissions from products.

For more information on Volatile Organic Compounds, refer to the Materials WELLography™.

1. Benzene

Benzene is a volatile organic hydrocarbon with the molecular formula C6H6.²³⁶ It is a natural component of crude oil and is found in gasoline and cigarette smoke. Benzene is colorless and highly flammable. It is used in the production of many common products, such as gasoline, plastic, rubber, and synthetic fabrics like nylon and polyester, however, in building materials used indoors it cannot be measured in the final product.²³⁶

Acute health effects associated with continued high levels of exposure to benzene over a significant period of time include neurological symptoms, as well as skin, eye, and lung irritation. Average lifetime cancer risk from exposure to 177 studied air pollutants (excluding radon) at typical outdoor levels is estimated to be between 1 in a million and 25 in a million. The biggest component of this risk, making up 25% of the total risk, is benzene, largely generated by vehicular traffic.²³⁷

Health Effects

Endocrine and Immune Systems

Leukemia. Benzene is classified as a Group 1 known human carcinogen by the IARC.²³⁸

An epidemiological case-control study of 79 individuals working in the Australian petroleum industry assessed the linkage between benzene exposure and the risk of leukemia.²³⁹ For a cumulative benzene exposure above eight ppm-years (parts per million–years), an increased risk of leukemia was found with an odds ratio of 11.3, and risk further increased with higher exposure.²³⁹

Another case-control study, with 765 cases of leukemia in children under the age of 15, found a significant association between acute childhood leukemia and residence near a gas station or auto repair garage (odds ratio of 1.9 and 1.6, respectively).²⁴⁰ The authors concluded that low-level benzene exposure has a role in the development of childhood leukemia.²⁴⁰

Nervous System

Headaches and fatigue. Chronic and acute exposure to levels above OSHA limits often leads to nervous impairment ²⁴¹. A study with 121 workers investigated the neurological impact of chronic exposure (6 to 15.6 ppm for two to nine years) to benzene. Over 60% of the workers complained of headaches, fatigue, difficulty sleeping, and memory loss. It should be noted that the workers in the study were also chronically exposed to toluene, but at levels lower than 1.5 ppm (5 mg/m³). The EPA also notes that exposure to high concentrations (250 to 3,000 ppm) of benzene can cause dizziness, headache, and vertigo.²⁴¹

Solutions

1. Pollutant Restriction and Abatement

The WHO recommends eliminating the use of benzene by promoting, “the use of alternative solvents in industrial processes, glues and paints,” as well as, “avoid[ing] domestic use of benzene-containing products”.²⁴²

2. Vehicle Idling Limits

Cars use more fuel and cause more engine wear when they idle for more than 30 seconds compared with turning off and restarting the engine ¹¹². In 1999, cars and trucks were responsible for almost half of all benzene emissions in the U.S.²³⁷ By limiting vehicle idling on nearby roads and driveways, buildings can reduce the local sources of VOC pollution.

3. Carbon Air Filtration

Carbon filtration has shown to be an effective method of removing airborne benzene. One study showed a 90% reduction in benzene when a steady flow of waste gas passed through a carbon filter at a steady rate of flow.²⁴³ Standalone air purifiers using a combination of activated carbon, photocatalytic filters, and manganese dioxide are effective at removing benzene from indoor air.²⁴⁴

2. Formaldehyde

Formaldehyde is used as a precursor in the production of many complex compounds and is used in many industrial applications.²⁴⁵ At room temperature, it is a gas.²⁴⁵ Exposure to formaldehyde in indoor environments can occur through off-gassing from wood-based products assembled with urea-formaldehyde, but can also come from paints, varnishes, floor finishes, or cigarette smoke.²⁴⁶ EPA reports that Salthammer et al. (2010) reviewed from studies from 2005 or later and concluded that typical indoor air levels are 16-32 ppb.²⁴⁷

The WHO has established exposure guidelines for formaldehyde in non-occupational settings at 100 ppb for 30 minutes.²⁴⁸ These are levels at which the risk of upper respiratory tract cancer in humans can be considered negligible.²⁴⁸ The U.S. Department of Housing and Urban Development sets indoor ambient formaldehyde levels at 400 ppb for manufactured homes, adding restrictions for component standards, plywood material emissions at less than 200 ppb and particle boards at 300 ppb.²⁴⁹

FIGURE 15: FORMALDEHYDE EXPOSURE RANGES.²⁵⁰

Health Effects

Nervous System

Sensory irritations. Formaldehyde generally causes eye irritation at 310 ppb. However, some sensitive individuals may experience symptoms at 100 ppb.²⁵¹

Neurobehavioral performance. Neurological effects of formaldehyde exposure have been observed in humans breathing 0.1 to 0.5 ppm.²⁵²

Respiratory System

Childhood asthma. According to the Agency for Toxic Substances and Disease Registry, there is a possible relationship between formaldehyde exposure the development of childhood asthma or asthma-like symptoms.²⁵² A systematic review of seven (mostly cross-sectional) studies included data on a possible association between formaldehyde exposure and asthma in children, suggesting a positive relationship between formaldehyde levels and childhood asthma (odds ratio of 1.17 per 10 µg/m³ increase.²⁵³

Respiratory diseases. A study of 298 children suggests a positive relationship between formaldehyde exposure and respiratory symptoms in children.²⁵⁴ The children completed questionnaires on chronic respiratory symptoms and had their peak expiratory flow rates measured up to four times per day, and formaldehyde levels in their homes were measured for two one-week periods. Peak expiratory flow rates were 10% lower with formaldehyde exposure levels as low as 30 ppb, with greater effects seen in children with asthma.²⁵⁴

Solutions

1. Operable Windows

Windows that can be opened by the people in the building or automated systems can rapidly increase the amount of outside air entering a building. While this is effective at reducing formaldehyde levels,²⁵⁵ care must be taken to avoid introducing ambient air, which may be higher in other pollutants, such as ozone and particulate matter.

The ATSDR measured formaldehyde levels in 96 temporary-housing trailers, very similar to those used for people displaced by Hurricane Katrina.²⁵⁶ They measured formaldehyde levels of 0.01 to 3.66 ppm, with an average of 1.04 ppm, in the closed and unventilated trailers. Opening the windows for two weeks led to significant reductions in formaldehyde levels, to 0.09 ppm (90 ppb) on average.²⁵⁶

2. Adequate Ventilation

The ATSDR measured lower formaldehyde levels in housing trailers with the air conditioning units running and found much higher levels in closed and unventilated trailers. Average levels of 0.39 ppm were measured in ventilated trailers compared to 1.04 ppm in closed and unventilated trailers.²⁵⁶

3. Material Constraints

The EPA suggests reducing the amount of indoor formaldehyde by buying composite-wood products that have been certified as compliant by the American National Standards Institute (ANSI) or the California Air Resources Board Airborne Toxic Control Measures (ATCMs) to Reduce Formaldehyde Emissions from Composite Wood Products.²⁵⁷

4. Carbon Air Filtration

Activated carbon filters are effective at adsorbing formaldehyde from the circulated air. The concentration of formaldehyde in air passing through these filters can be reduced by 20% with total removal efficiency up to 40%.²⁵⁸ In buildings without central air systems, standalone air purifiers using a combination of activated carbon, photocatalytic filters, and manganese dioxide have also been shown to be effective at removing formaldehyde from indoor air.²⁵⁵

5. Controlling Temperature

The ATSDR found a highly positive correlation between formaldehyde levels in temporary-housing trailers and indoor temperature (with windows closed): Formaldehyde levels when the trailer was at 80°F were twice as great compared with when it was at 70°F.²⁵⁶ The EPA suggests that high temperatures accelerate formaldehyde emissions from indoor sources,²⁵⁷ for example during building pre-occupancy period.

6. Controlling Humidity

Keeping humidity levels low can decrease indoor formaldehyde emissions. A study carried out chamber experiments with sample materials from trailers and found that an increase of relative humidity up to 35% led to increased formaldehyde emissions from the materials by a factor of 1.8–2.6.²⁶⁰ An additional study found a positive correlation between the emission rate of formaldehyde found in building materials and absolute humidity, with high humidity associated with greater emission rates.²⁶¹

7. Kitchen Exhaust Hoods

Gas stovetops and ovens produce formaldehyde. Venting hoods over the stove can greatly reduce this pollution.¹¹¹

Polycyclic Aromatic Hydrocarbons (PAHs)

Polycyclic aromatic hydrocarbons are atmospheric pollutants consisting of two or more fused hydrocarbon rings.²⁶² PAHs are very widespread organic pollutants and originate from combustion processes in both indoor and outdoor sources such as vehicle exhaust, cigarette smoke, home heating, and laying tar. According to the WHO, “life-long exposure to PAHs at concentrations commonly observed in European or North American cities is associated with up to 50 excess cases of lung cancer per 1,000,000 people”.²⁶²

1. Benzo[a]pyrene (BaP)

Benzo[a]pyrene (BaP) is one of the most potent carcinogenic PAHs. The risk of PAH exposure is higher in houses with smokers or other forms of indoor combustion and improper ventilation.²⁶² WHO does not consider any detectable levels of BaP to be safe.²⁴⁸ The EPA does not regulate BaP in air, but OSHA’s permissible eight-hour average is 200 µg/m³, and NIOSH’s recommended exposure limit is 100 µg/m³ average over a 10-hour period.²⁶³

Health Effects

Endocrine System

Multiple cancers. BaP is associated with chromosomal replication errors, leading to multiple types of cancer.²⁶⁴

Reproductive and Endocrine Systems

Fetal abnormalities and death. Fetal exposure to BaP is associated with developmental abnormalities, as well as with an increased incidence of tumors later in adulthood.²⁶⁴ Given the greater likelihood to play in and around soils contaminated with BaP, children are at higher risk of exposure than adults.²⁶⁴

Nervous System

Cognitive development. A 2012 study found a correlation between prenatal exposures to New York City’s environmental PAH levels and symptoms of anxiety/depression and attention problems in 253 children, ages six and seven.²⁶⁵ PAH exposures of nonsmoking women during pregnancy as well as BaP-specific biomarkers in subjects’ maternal and cord blood were measured, and their children’s development was assessed using the Child Behavior Checklist (CBCL). The study found an association between increased prenatal exposure to PAHs and anxiety/depression as well as attention problems on the CBCL. It further concluded that maternal exposure could impact the children’s cognitive development and ability to learn.²⁶⁵ Additionally, a 2015 prospective cohort study of 40 children found an association between prenatal PAH exposure and changes in cognition and behavior in childhood. Specific effects included slower processing speed, symptoms of ADHD, and externalizing problems (which include maladaptive behaviors that individuals direct towards their environment).²⁶⁶

Solutions

1. Kitchen Exhaust Hoods

Frying, broiling, and sautéing are major sources of indoor PAH. Venting hoods over the stove can significantly reduce this pollution.¹¹¹ ²⁶⁴

Smoking

In 2013, an estimated 42.1 million people (or 17.8% of adults) were cigarette smokers in the U.S.²⁶⁷ Worldwide, there are more than one billion tobacco smokers, nearly 80% of whom come from low- or middle-income countries.²⁶⁸ Based on the EPA’s 24-hour air quality data from 2007 to 2009, it is estimated that the inhalation of ambient PM2.5 in Los Angeles (~343 µg a week) is equivalent to smoking four cigarettes.¹²⁶

1. Tobacco Smoke

Cigarettes are the most common tobacco consumption method, but other tobacco products are gaining popularity. In India, a type of cigarette called a bidi, which is tobacco wrapped in a leaf, is more popular than a regular cigarette. In Indonesia, the kretek is a common type of tobacco cigarette that is blended with cloves. Shisha, a blend of fruits, oils, and dried plants smoked in a water pipe known as a hookah and originating from the Middle East is growing in popularity around the world.

The majority of tobacco products contain the compound nicotine, which is rapidly delivered to the brain when inhaled. Because nicotine is habit-forming, long-term smoking makes quitting difficult due to the withdrawal symptoms associated with cessation. In addition to nicotine, cigarettes contain about 600 ingredients that form over 7,000 compounds when burned, at least 69 of which are known to be carcinogenic.²⁶⁹ However, the consequences related to tobacco smoke usually do not manifest until many years after beginning smoking.²⁷⁰

The number of smokers worldwide is expected to continue increasing.²⁷¹ WHO estimates that six million people a year die from smoking.²⁶⁸ Smoking-related deaths could reach eight million per year by 2030 if the growth rate for smoking tobacco products does not slow.²⁷²

According to the WHO, 18% of the world’s population today is protected by smoke-free laws. Smoke-free legislation has been implemented in large parts of the U.S., Canada, Europe, South Africa, Australia, Brazil, India, and other countries.²⁷³ These policies are enforced in schools, private and public workplaces, and public spaces, and are vital in helping prevent the dangers of secondhand smoke of which there is no safe exposure level.²⁷⁴ In addition to smoking, secondhand smoke is a serious and preventable cause of morbidity and mortality, and since 1964 has been the cause of over 2.5 million deaths among nonsmoking individuals in the U.S. alone.²⁷⁴

Health Effects

Respiratory System

Chronic obstructive pulmonary disease (COPD). As an active (mainstream) and passive (second hand) inhalant, tobacco smoke has direct adverse effects on the respiratory system COPD.²⁷⁵ COPD, which includes emphysema, was the first respiratory-related illness linked to smoking in the Surgeon General’s 1964 report. Annually, approximately 127,600 deaths in the U.S. are attributed to smoking-induced COPD.²⁷⁵

Tuberculosis (TB). While tuberculosis is no longer a prevalent disease in the U.S., it is still a prominent threat in the developing world. A nested case-control study in India compared the smoking practices of 85 men with tuberculosis to 459 randomly selected age- and gender-matched controls and found a positive association (odds ratio of 2.48) between tobacco smoking and tuberculosis.²⁷⁶ The association had a strong dose-response relationship, indicating that smokers are more likely to catch tuberculosis than nonsmokers.²⁷⁶ A prospective cohort study of 17,699 Taiwanese individuals found that smoking tobacco was associated with a twofold increased risk of active tuberculosis. Additionally, researchers identified a significant dose-response relationship for cigarettes smoked per-day, years of smoking, and pack-years with the risk of active tuberculosis.²⁷⁷

Respiratory and Immune Systems

Asthma. A large prospective cohort study in Germany of almost 3,000 individuals observed an association between smoking and incidences of wheezing or diagnosed asthma.²⁷⁸ Subjects, aged 9 to 11 years at the beginning of the study, underwent medical assessment and received follow-up questionnaires assessing their health and living conditions approximately seven years later. Compared with nonsmokers, smokers had an increased risk ratio of 2.76 for wheezing (without a cold) and a 2.56 increased risk ratio for diagnosed asthma.²⁷⁸

Respiratory and Endocrine Systems

Lung cancer. Smoking tobacco products can lead to the development of lung cancer, the most common cancer associated with smoking. Lung cancer is estimated to have been responsible for 137,989 deaths in the U.S. between 2005 and 2009, or approximately 29% of all smoking-attributable deaths.²⁷⁵ The risk of lung cancer associated with smoking has increased over time, presumably due to changes in the ingredient composition of cigarettes.²⁷⁹

Digestive and Endocrine Systems

Colorectal cancer. Cancer of the colon or rectum, sections of the lower intestinal tract, has been added to the health effects causally linked to smoking in the 2014 Surgeon General’s Report.²⁸⁰ A review of 27 studies found a positive association between smoking and an increased risk of colorectal cancer. Furthermore, it is estimated that one out of five cases of colorectal cancer in the U.S. may be attributable to tobacco use.²⁸¹

Liver cancer. Many studies have confirmed a causal link between smoking and an elevated risk of liver cancer. A 2009 meta-analysis of studies examining the link between smoking and liver cancer confirmed that smoking increases the risk of liver cancer.²⁸² Additionally, the U.S. Department of Health and Human Services and the IARC both note a positive relationship between smoking and liver cancer.²⁸⁰ ²⁸²

Endocrine System

Type 2 diabetes. A systematic review and meta-analysis of 25 prospective cohort studies with 1.2 million participants and almost 46,000 incidences of diabetes over 5 to 30 years found a positive association between smoking status and type 2 diabetes.²⁸³ The pooled adjusted relative risk of developing type 2 diabetes for a smoker was 1.44 times that of a nonsmoker. Additionally, a dose-response relationship was observed, with lighter smokers experiencing lower risks compared to heavy smokers.²⁸³

Cardiovascular System

Cardiovascular disease. Cardiovascular disease is responsible for a significant portion of smoking-attributable deaths in individuals 35 years of age or older in the U.S.²⁸⁰ Exposure to tobacco smoke is associated with accelerated atherosclerosis and increased risk of acute myocardial infarction, stroke, aortic aneurysm, peripheral arterial disease, and sudden death. The risk of cardiovascular disease rises sharply with the use of tobacco or consistent exposure to secondhand smoke.²⁸⁰

Reproductive System

Erectile dysfunction. The 2014 Surgeon General’s Report indicates that there is sufficient evidence to demonstrate a causal relationship between smoking and male sexual dysfunction.²⁸⁰ Studies indicate a plausible mechanism by which tobacco may be responsible for altering the blood flow that is required for an erection to occur, similar to the effects of heart disease on coronary circulation.²⁸⁰

Birth defects. A systematic review of published scientific literature from 1959 to 2010 identified 172 articles that reported an association between non-chromosomal birth defects and smoking during pregnancy.²⁸⁴ The data, which included almost 175,000 cases and more than 11.6 million controls, found that smoking during pregnancy was associated with increased risk of limb reduction defects (odds ratio of 1.26), clubfoot and orofacial clefts (odds ratio of 1.28), defects of the eyes (odds ratio of 1.25), and gastrointestinal system (odds ratio of 1.27).²⁸⁴

Immune System

Rheumatoid arthritis. It is likely that environmental factors contribute to the development of rheumatoid arthritis (RA), a severe inflammatory arthritis. A prospective analysis of over 100,000 women (of whom 680 were diagnosed with RA) explored the risk of developing RA among current or former smokers and those who had never smoked.²⁸⁵ Compared to those who had never smoked, the relative risk of developing RA among current and former smokers was 1.43 and 1.47, respectively.²⁸⁵

Nervous System

Age-related macular degeneration (AMD). According to the 2014 Surgeon General’s Report, there is sufficient evidence to infer a causal link between smoking and an increased risk of AMD.²⁸⁰ While the risk of AMD is greatest for current smokers, there is also a significantly greater risk for former smokers compared to individuals who have never smoked.²⁸⁰

Solutions

1. Smoking Ban

To protect people from secondhand smoke, smoking should be prohibited in all (indoor and outdoor) public spaces. Smoke-free laws are already enforced in many schools, private and public workplaces, and public spaces around the world.²⁷³

A systematic review of smoke-free policies by the CDC’s Task Force on Community Preventive Services found strong evidence that these types of policies not only reduce the prevalence of tobacco use, exposure to secondhand smoke, initiation of tobacco use among youth, and tobacco-related morbidity and mortality, but they also increase the number of individuals who quit using tobacco products.²⁸⁶ Similar results were found in the Surgeon General’s 2014 report, The Health Consequences of Smoking—50 Years of Progress,²⁸⁰ as well as a report by the Campaign for Tobacco-Free Kids.²⁸⁷

Research evaluating the effects of smoke-free legislation suggests that these policies have positive effects on respiratory health²⁸⁸ and lower the risk of smoking-related cardiac and cerebrovascular diseases.²⁸⁹ A systematic review of smoke-free workplaces concluded that these policies reduce total cigarette consumption per employee by 29%.²⁹⁰ In one study, researchers tracked the number of respiratory and cardiovascular hospital admissions attributable to smoking after the implementation of smoking bans. These numbers were compared to admissions in counties without smoking bans, as well as admission rates prior to the smoke-free legislation. The study found that after the implementation of smoking bans, hospital admission rates for cardiovascular and respiratory-related diseases decreased by 39% and 33%, respectively.²⁹¹

A major benefit of no-smoking policies is protecting people from the harms of secondhand smoke. Additionally, smoking bans have been shown to have significant effects on reducing levels of various chemicals associated with tobacco smoke in indoor environments. An exposure study linked the introduction of a smoking ban in Ireland to a reduction of benzene levels in 26 Dublin pubs by 80.2%, and a reduction of PM2.5 levels in 42 pubs by 83%.²⁹² Additionally, a study conducted in Rome, Italy noted a decline in UFPs in hospitality venues after the implementation of an indoor smoking ban.²⁹³ Mean amounts of UFPs in the 47 establishments dropped from 76,956 pt/cm³ (particles per cm³) before legislation to 51,692 pt/cm³ 12 months post-legislation.²⁹³ Another study measured particle-bound PAHs (PPAHs), including BaP, in seven Boston pubs before and after the implementation of a smoking ban (ventilation rates in the pubs were within ASHRAE design parameters). In six of the seven pubs, PPAH levels were 10 times higher before the smoking ban (61.7 ng/m³) than afterward (6.32 ng/m³).²⁹⁴ Finally, a study in Saõ Paolo, Brazil measured CO levels in 585 hospitality venues before and 12 weeks after the implementation of smoke-free legislation. After implementing the smoking ban, the mean indoor CO levels had dropped from 4.57 ppm to 1.35 ppm, and in open areas, they had decreased from 3.31 ppm to 1.31 ppm.²⁹⁵

2. Smoking Cessation Programs

Smoking cessation programs, which include counseling and the use of FDA-approved medications, have been shown to reduce smoking rates successfully.²⁹⁶ ²⁹⁷ In addition to behavior change, there may be economic benefits associated with reduced smoking rates. One study concluded that on average, U.S. employers pay an additional $5,816 for each smoker on their payroll.²⁹⁸ Furthermore, some research estimates that smoking contributes to over $150 billion in productivity losses in the U.S. each year.²⁹⁸

Particle Filters

Ventilation expels indoor air and replaces it with outdoor air.⁷⁴ If the replacement air contains ozone, diesel particulate matter, or other pollutants, the air ducts will simply deliver dirty air back into the building. In order to prevent this from happening, ventilation systems require filtration. Different filters address different contaminants and are best used in combination (Figure 16).⁷⁴

FIGURE 16: A MULTISTAGE APPROACH TO CLEANING AIR.⁷⁴

Media Filteration. ASHRAE, in its Standard 52.2, assigns filters a Minimum Efficiency Reporting Value (MERV).⁴³ The MERV number describes the number of different types of particles a filter removes when operating at the least effective point in its life. Although somewhat counterintuitive, filters become increasingly effective over time, as particles lodge in the mesh, reducing the open areas through which some may be able to pass in a newer, cleaner filter. This increased particle loading has increasing energy requirements, as more effort is required to push air through the filter.

Figure 17 summarizes the effects that different MERV filter levels have on air quality. In each category, the filter removes at least 85% of all contaminants larger than the range listed and a smaller fraction of those particles within the range.⁷⁴ Within each level grouping, filters with higher designations (8, 12, etc.) remove more of the contaminants of the listed size.⁴³ ⁷⁴

FIGURE 17: CLASSIFICATION OF MERV RATINGS⁷⁴

MERV 1 to 4 do not address most of the particles harmful to people and are mainly used to protect mechanical and electronic devices. ASHRAE standards require any building with a central HVAC system to use MERV filters of level 8 or higher.⁷⁴

Filters with MERV levels between 17 and 20 and are used in cleanrooms and pharmaceutical manufacturing facilities.⁷⁴ Due to their typical use in scientific rather than commercial, residential, and institutional buildings, High Efficiency Particulate Air (HEPA) filters are governed by the Institute of Environmental Sciences and Technology rather than ASHRAE.⁷⁴ HEPA’s extreme filtration results in a large pressure drop, which limits the quantity of air the device, can filter. As a result, these filters are often installed in bypass configuration, which provides high-quality filtration to a portion of the air, while leaving the remainder untreated. This process can result in unfiltered outside air circumventing the HEPA filter and entering the building.⁷⁴

Freestanding air purifiers can remove impurities from a limited quantity of air through a variety of treatment and filter technologies. They provide flexibility of application where there are no ducts and air handlers, but can typically only clean the air in a single room.

Electrostatic Filters. By imparting a charge to airborne particles, electrostatic filters can then attract particulate matter and remove the particles from the air.²⁹⁹ The gaps in the mesh are larger than in media filters, which allow more airflow for a given design of fans, while the electric adhesion maintains filtration capacity. However, the use of low-efficiency filters upstream can remove the large particles before they reach the mesh and therefore help control ozone generation. When used and maintained properly, ozone molecules produced by electrostatic systems usually decay before reaching unhealthy concentrations.²⁹⁹

Carbon Air Filtration. Carbon air filters work by adsorbing many organic and reactive airborne contaminants.³⁰⁰ Carbon filters remove most gaseous contaminants, except CO, and must be preceded by traditional filters to remove particulates that would otherwise clog their pores. Typical carbon filters can be installed directly into ducts and last 6 to 12 months if used with dust-free air. They are also often included in freestanding air purifiers.

Ultraviolet Germicidal Irradiation (UVGI)

UVGI is a disinfection technique that can effectively destroy microorganisms (or prevent them from replicating) by using short wavelength UV waves, thus causing DNA damage.³⁰¹ UVGI systems usually use low-pressure mercury discharge lamps that emit 254-nanometer wavelength UV rays. In addition, the lamps produce some visible light that humans see as blue light.³⁰¹ UVGI systems are often used in crowded environments and are installed in the ductwork of ventilation systems as well as in the open spaces in the upper parts of the room. To prevent human exposure to UV rays, the source of the rays has to be shielded.³⁰¹ Additionally, the area in which UV irradiation takes place should be adequately ventilated, as ozone can be generated by UV light.

UV treatment aids in stopping the spread of microscopic life rather than purifying the air, as it does not remove dead biological contaminants that can still trigger allergies.

Photocatalytic Oxidation (PCO)

Photocatalytic oxidation is a reaction between a surface coating, such as titanium dioxide (TiO2), and oxygen to turn VOCs into CO2 and to kill and decompose bioaerosols.³⁰² PCO can be active or passive. Active PCO systems use a high-surface area support that is irradiated with ultraviolet light in order to trap VOCs in HVAC systems. Under UV irradiation, the compound then reacts with a coating applied to the support and converts the undesirable contaminant to CO2 and water (or other end products).³⁰² Passive PCO systems, which are still in the experimental stages of development, are similar to active ones. Instead of being incorporated into HVAC systems and using UV light, they are incorporated into building surfaces (e.g., painted walls) and use ambient light to activate the catalysts.³⁰²

Dehumidification

Dehumidifiers are devices used for removing moisture from the air in order to reduce the potential for growth of molds or dust mites.⁴⁹ Dehumidifiers are especially useful in environments that tend to collect humidity, such as garages and basements.⁴⁹ Dehumidifiers work by taking in air and running it through cold coils, thus causing any moisture from the air to condense. The air is then passed on to warm coils and out into the room. The water that condenses on the coils is collected and empties into a drain or has to be emptied manually.⁴⁹

The EPA recommends that to prevent the establishment and growth of indoor pests, relative humidity indoors should be kept between 30% and 50%.⁹² Humidity toward the bottom of the range is better in terms of air quality, but extremely low moisture levels may lead to dry or itchy skin, eyes, or throat.³⁰³

Smoking Ban

Smoking bans are laws and policies that prohibit the use of tobacco in public buildings and spaces, workplaces, schools, campuses, restaurants, hotels, hospitals, and other indoor and outdoor venues. Cities can regulate smoking through tobacco-specific legislations or regulations. Alternatively, they can look to the existing labor, occupational health and safety, human rights, and environmental statutes, as well as other regulatory instruments, to implement or enforce smoke-free rules.

Effective protection from exposure to tobacco smoke requires total smoke elimination.²⁷⁴ This means that only 100% smoke-free environments are adequate at protecting people from the harms of exposure to secondhand smoke. Separated indoor smoking areas, even if separately ventilated, are not an effective solution.²⁷⁴

Smoking Cessation Programs

Smoking cessation programs are meant to help smoking individuals quit smoking through the use of counseling and/or FDA-approved medications. They have been shown to reduce smoking rates, the number of cigarettes smoked, and exposure to secondhand smoke, and should be included as a workplace wellness program or benefit covered by employer-provided health insurance.²⁹⁷

Cessation programs can include group or individual classes, counseling sessions, and telephone quit lines that educate and support smokers who would like to quit.²⁹⁶ In addition, educational materials can be made available either in hard copy or as online resources. Cessation programs may also include FDA-approved medications as another tool to aid smokers in quitting.³⁰⁴

Walk-off Entry System

Walk-off entry systems employ specific surfaces to capture the dirt and pollutants that can be tracked indoors by shoes or clothes.³⁰⁵

When choosing a walk-off system, the individual needs of the space should carefully be evaluated. Weather conditions, number and frequency of visitors, and entryway size must be considered, as the choice of system can have implications for overall cleaning and maintenance costs. Depending on these variables, mats can have more scraping or wiping properties and varying moisture absorbing qualities. Entryway walk-off systems can also consist of metal grating to remove heavy dirt. An additional benefit is that mats can play an important role in providing safety on slippery surfaces.

The matting manufacturing company Notrax estimates that in public buildings with high pedestrian traffic, 1,000 people can deposit up to 24 pounds of dirt on entryway matting over a 20-day period. Matting can assist in removing up to 80% of dirt.³⁰⁵

Efficient and Healthy Cleaning Routine

To maintain a people-friendly and healthy environment, a regular cleaning routine, including vacuuming, sanitizing, and disinfecting of floors and surfaces, is essential.

In a double-blind intervention study from 2004 with 114 nonsmoking participants who had recently been complaining of mucosal irritations, it was shown that the intervention group, whose office spaces were comprehensively cleaned, compared with the control group whose spaces underwent a placebo treatment, experienced a reduction in irritation symptoms, as well as in nasal congestion.³⁰⁶

A long-term study monitoring the indoor environment of a nonproblem, multi-floor building suggests that an improved cleaning program has positive effects on indoor air quality by reducing airborne dust mass, total VOCs, and levels of culturable bacteria and fungi.³⁰⁷

Material Constraints

Building materials, furniture, fabrics, office equipment, and finishes should be chosen carefully after analyzing the material composition and known associated health impacts. Bans of certain toxic materials such as asbestos and lead are relatively obvious constraints, but many indoor objects perceived as safe may also emit pollutants such as VOCs, thus contributing to a hazardous background level of indoor air pollution.¹⁰ Composite materials that are well known to off-gas formaldehyde and low-level pollution can gradually add up to potentially adverse exposure levels.

Furthermore, VOCs can leak out of closed cans and sprayers filled with household cleaners, making it necessary to keep these products in areas that do not interact with house air.¹⁰

Protection and Care During and Following Construction

Construction processes often produce large amounts of dust and other pollutants. As such, areas undergoing renovation or construction should be given special consideration in order to minimize the creation of additional indoor pollution construction.³⁰⁸

High dust contamination can be a strain for any existing HVAC system and lead to the exhaustion of installed filters. Moreover, certain materials can adsorb VOCs and other particles set free during construction.³⁰⁸ Therefore, it is advisable to physically protect some areas from pollution exposure in order to minimize the spread and adsorption of pollutants throughout the building and onto furnishings and materials. Keeping this in mind, intelligent use of existing mechanical systems, careful construction sequencing, and a thorough cleanup after finalization of building procedures are recommended measures when renovating an indoor environment.

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Air a WELLography™ First Edition

Table of Contents

Copyright

Credits

Acknowledgements

Discalimer

Welcome to WELL

How to Use This WELLography™

Introduction

Air and the Built Environment

Air and the Human Body

The Atmosphere

Human Respiratory System

Airborne Toxin Exposure and Some Common Health Conditions

Elements of Air Contaminants

Particulate Matter Derived from Plants and Animals

1. Plant- and Animal-based Particulates

Health Effects

Solutions

2. Dust Mites, Cockroaches, and other Pests

Health Effects

Solutions

Microbial Pathogens

1. Bacteria

Health Effects

Solutions

2. Viruses

Health Effects

Solutions

3. Fungi (Mold)

Health Effects

Solutions

Particulate Matter

1. Coarse Particulate Matter (PM10)

Health Effects

Solutions

2. Fine Particulate Matter (PM2.5)

Health Effects

Solutions

3. Ultrafine Particles (UFPs)

Health Effects

Solutions

Specific Airborne Particles and Fibers

1. Diesel Exhaust Particulate Matter

Health Effects

Solutions

2. Lead Particulates

Health Effects

Solutions

3. Mercury Particles

Health Effects

Solutions

4. Asbestos Fibers

Gases

1. Cardion Dioxide

Health Effects

Solutions

2. Carbon Monoxide

Health Effects

Solutions

3. Ozone

Health Effects

Solutions

4. Nitrogen Dioxide

Health Effects

Solutions

5. Radon

Health Effects

Solutions

Volatile Organic Compounds (VOCs)

1. Benzene

Health Effects

Solutions

2. Formaldehyde

Health Effects

Solutions

Polycyclic Aromatic Hydrocarbons (PAHs)

1. Benzo[a]pyrene (BaP)

Health Effects

Solutions

Air a WELLography™
First Edition