Indoor Air Quality + Physiological Health

I. Indoor Air Quality - Introduction

Over the past 20 years, building envelopes have become more airtight and thermally efficient due to increasingly stringent building regulations (Allen 2016) aimed at reducing energy consumption and carbon emissions. While tighter envelopes reduce energy consumption due to reduced infiltration of outside air, low ventilation rates are associated with increased concentrations of indoor pollutants that can be detrimental to health, productivity, and wellness (Gerardi 2010).

II. Impact

Considering humans spend nearly 90% of their lives indoors, the potential impact of indoor air quality within homes, schools, offices or other building environments on human health is important to consider (EPA ROE). Poor indoor air quality can lead to illness, causing medical expenses and absenteeism from work and school. Human health can be affected by indoor pollutants generated from viral, bacterial, fungal, or animal protein sources. Some building materials and consumer products also release volatile organic compounds (VOCs) and chemical pollutants like formaldehyde, which can cause detrimental health effects (Cedeno-Laurent et al. 2018). Diluting indoor pollutants through effective ventilation can reduce the effects of pollutants on occupant’s health. The most common building-related illnesses with a clear clinical diagnosis are respiratory infections and asthma. Indoor pollution also causes fatigue, irritation, headaches and other Sick Building Syndrome (SBS) symptoms (Gerardi 2010, Cedeno-Laurent et al. 2018).

In this brief, we focus on measurable human health impacts of IAQ. Related, but more subtle shifts in IAQ, and their impact on human performance and productivity are discussed within the IAQ Productivity Brief.

III. Indoor Pollutants

Indoor air pollutants can be classified as volatile organic compounds (VOCs), particulate matter, infectious agents, allergens and gases. (Gerardi 2010). High levels of these indoor pollutants are associated with health effects, especially for people with existent asthma or other respiratory problems (MacNaughton 2015).

VI. Volatile Organic Compounds

VOCs are known indoor irritants which often have unpleasant odors and have been linked to fatigue, difficulty concentrating, respiratory problems, and cancer (Gerardi 2010, Bernstein 2008, Fisk 1997). Chemical VOCs such as Formaldehyde are predominantly emitted by office furniture, cabinetry, carpet tile, vinyl wall coverings, paints, and adhesives (Bernstein 2008). A review by Bernstein et al. discusses that the primary adverse health associations with VOCs have been symptoms of mucous membrane irritation and systemic effects such as fatigue and difficulty concentrating, and that occupants almost always complain at high levels above 3000μg/m3. Microbial VOCs can be released from mold or mildew caused by moisture accumulation and have been associated with adverse health effects such as eye, nose and throat irritation, coughing, wheezing, fatigue, headache, dizziness, and nausea (Bernstein 2008).

V. Allergens

Non-mold allergens (dust, pet and rodent dander, cockroach antigens, foods) and mold allergens both cause adverse health effects when present indoors. The smaller size of non-mold allergens can penetrate deeper into the lungs causing respiratory aggravation (Gerardi 2010). Unwanted water and moisture indoors can cause favorable conditions for mold growth (Cedeno-Laurent et al. 2018), which has been attributed as a main source of building-related Illnesses (OSHA). In a meta-analysis of studies related to occupant health in schools or day care centers with dampness or mold, Fisk et al. drew associations to moderate increases in health risks for cough (32%) and wheezing (68%), and small increases for nasal symptoms (20%) when dampness or mold was observed (Fisk 2019).

VI. Particulate Matter (PM)

Particulate matter is notable for the small sizes of airborne particulates that can carry absorbed toxins deep into the lung, causing respiratory implications including aggravation of existing bronchitis, asthma, and allergies. Sources include diesel engines, heating appliances, road dust, wildfire smoke, construction debris, and consumer products (Gerardi 2010).

VII. Gases

Nitrogen dioxide (NO2) is an indoor pollutant that is produced by human activity and is typically generated by heating and cooking appliances. Nitrogen dioxide can cause serious damage to the respiratory tract and exacerbate asthma (Gerardi, 2010). Carbon Monoxide is a colorless, odorless, nonirritating gas that can be produced by heating appliances, causing fatigue, headaches, dyspnea, loss of consciousness and death (Gerardi, 2010).

Carbon dioxide (CO2) is produced at a rate of 35,000 – 50,000 ppm per breath, which is 100 times higher than the concentration of typical outdoor air (WSU Energy Program Report 2013). For this reason, CO2 can be used as an indicator of building ventilation rates, as indoor CO2 will rise substantially beyond outdoor levels in an occupied building if ventilation rates are low. CO2 is also an indicator of accumulation of indoor pollutants such as VOCs and particulates (Vehviläinen et al. 2016, Allen 2016, Maddalena et al. 2015). CO2 has been linked to decreased cognitive performance at levels below 1000 ppm (Allen 2016) and increased rates of Sick Building Syndrome symptoms beginning at 1000ppm and above, shown in Table 1 (Vehvilainen 2016, Apte 2000, Wallingford 1986). Higher CO2 concentrations ranging from 2,000 – 4,000 ppm cause elevated concentrations of pCO2 in human tissues, changes in heart rate variation and increase peripheral blood circulation leading to symptoms of headaches, sleepiness, and changes in body temperature (Vehviläinen et al. 2016). Air quality has been shown to be noticeably unpleasant and make people more exhausted when CO2 concentrations are beyond 3,000 ppm (Kajtar 2011). Impacts of CO2 below 1000ppm have been shown to impact cognitive performance, as discussed in the IAQ Productivity brief.

VIII. Sick Building Syndrome (SBS)

Sick Building Syndrome (SBS) is a common acute condition triggered by indoor pollutants with symptoms ranging from irritation of sinuses, dull headache, rash, and fatigue (Gerardi 2010, Kajtar 2011, Cedeno-Laurent et al. 2018). The primary factors affecting SBS related symptoms are outdoor ventilation rates, temperature, humidity, dust, and the microbial content of the air (Burge 2004). Burge surmises in a literature review that adjusting a single factor may not result in an immediate treatment for symptoms, but that the factors may work in association with one another. SBS symptoms subside when exposure to indoor irritant ends (Burge 2004). Evidence suggests low ventilation rates are associated with respiratory health effects, such as mucosal and allergy symptoms and can trigger additional respiratory problems in adults and children (Fisk 2017). Increase in ventilation rates in office settings has shown to decrease SBS symptoms (Heerwagen 2000, Apte 2000, Shan 2016).

IX. Asthma

Asthma is an ailment associated with poor indoor air quality and disproportionately impacts low-income and racial minority children (Gauderman 2005). In a Center for Disease Control study, the economic burden of asthma was estimated to be more than $80 billion per year (Nurmagambetov 2018). A major factor in the development and exacerbation of asthma is exposure to indoor allergens and irritants such as dust, particulates, mold and moisture, with as much at 40% of the excess asthma in minority children attributed to exposure to indoor allergens (Lanphear 2001). The Seattle Housing Authority, an entity that provides low income housing in Seattle, implemented the Breath Easy Program in 2003 in an effort to reduce asthma and other ailments associated with poor indoor air quality. Breathe Easy homes are new and renovated housing projects that improve indoor air quality through enhancing exterior envelope, replacing off-gassing indoor materials, and installing energy recovery ventilators with continuous fresh air supply (Takaro 2011). A study found that Breath Easy homes reduced asthma related clinical visits from 62% to 21% and nearly eliminated exposure to mold, rodents, and moisture (Takaro 2011).

X. Ventilation + IAQ

Bringing outdoor air into a building has the potential to significantly reduce the adverse effects of indoor air pollutants by reducing their concentration in indoor air (Gerardi 2010). While high ventilation rates above code minimums have been shown to improve air quality and health outcomes (Fisk 2017, Tarantini 2017), many buildings do not ventilate according to minimum ASHRAE standards (Mendell 2013, Allen 2016). Despite the health implications of indoor air contaminants, ASHRAE designates required ventilation rates based on perception of indoor air quality rather than relative risk of exposure (Lin 2014). The ASHRAE Standard 62.1 per person ventilation rates are based on bioeffluent concentration with which 80% or more of the occupants express satisfaction with air quality (ANSI/ ASHRAE 62.1-2019). Many studies have shown benefits in health and performance when increasing ventilation rates beyond ASHRAE standards (Mendell 2013, Allen 2016). An earlier study by Mendell indicated that ventilation rates 6-17cfm/person above the 20cfm/person guidance for offices at the time was effective in reducing building-related health symptoms, but further benefits were not evident from higher ventilation rates, suggesting that an upper threshold might exist (Mendell 2005).

XI. Ventilation + Spread of Airborne Infectious Disease

Multiple studies have indicated that increasing ventilation rates with outdoor air reduces the spread of airborne infectious disease by diluting bacterial and viral load in indoor air (Seppannen 1999, Li 2007). Recirculating inside air and low outside air ventilation rates can aide in the transmission of infectious diseases (Wargocki 2002). This benefit is realized only if the outdoor air brought into the building does not contain high concentrations of common outdoor pollutants such as particulate matter, ozone, and nitrogen oxides. These outdoor pollutants are associated with pediatric asthma, pulmonary inflammation, and decreased lung function and can enter buildings in high levels (Laumbach 2010, Roy 2011). MERV 13 filters are highly effective in filtering particulate matter and airborne bacteria and viruses, and can reduce these indoor pollutants by up to 95%. A recent paper echoes these findings (Bahnfleth et al. 2020). To prevent the spread of viruses such as SARS-CoV-2, Bahnfleth suggests building engineering control methods should be employed, including increased existing ventilation rates/outdoor air exchange rates, enhanced filtration and disinfection, and avoiding air-recirculation within the ventilation system when able (Bahnfleth et al. 2020). During the COVID-19 pandemic, ASHRAE has recommended significant increases in ventilation rates (ASHRAE). These mitigation strategies are detailed in ASHRAE guidelines for responding to SARS-CoV-2/COVID-19 (ASHRAE). This research is evolving as more information becomes known on the virus.

A literature review performed by Seppanen et al. identified three studies investigating the prevalence of respiratory illness in relation to ventilation rates (Seppanen 1999). The studies took place in military barracks, a jail, and a nursing home, and evaluated ventilation rate changes between 2.5 versus 20 cfm per person, 8 versus 26 cfm per person, and 4 versus 8 cfm per person respectively. In all three studies, lower ventilation rates yielded an increase in the rate of illness, ranging from 50% to 370%. Another literature review of indoor airflow and transmission rates of infectious diseases performed by a panel of medical experts and building scientists concluded that the spread of infectious diseases, such as measles, tuberculosis, chickenpox, influenza, smallpox, and SARS, increases with decreased ventilation (Li 2007). This panel was not able to provide conclusive recommendations on ventilation rates based on the findings of available studies, but an inverse relationship between infection rate and ventilation rate was observed.

XII. Ventilation + Absenteeism

Increasing ventilation rates has also been shown to decrease absenteeism in school and office settings. A study of 162 classrooms in 28 Californian schools in three school districts found that all school districts had median ventilation rates lower than the 7.1 l/s per person standard in California (Mendell 2013). Increasing classroom ventilation rates to the California standard in these classrooms was shown to decrease illness related absence by 3.4%. Another study found that doubling of ventilation rate in an office space from 25 to 50 cfm per person led to a 35% decrease in short term absence (Milton 2000). These results echo other studies that increased ventilation rates greatly benefit occupant health and reduce sickness related absence in work and school settings (Mendell 2005, Wyon 2004, Wargocki 2000, Fisk 2017, Allen 2016).

A LEED Gold certified office refurbishment for 150 employees that improved indoor air quality through enhanced outdoor air ventilation, continuous monitoring of CO2, and avoiding VOC emitting materials saw an annual savings of $85,000 per year due to a 44% reduction in absenteeism (World GBC 2018). An internal survey of employees at the company revealed the reduction in absenteeism largely due to a 64% reduction in reported allergy problems and 68% reduction in respiratory problems (Laski 2018).

XIII. Ventilation + Energy + Diminishing Returns for IAQ

While higher ventilation rates may improve health and productivity, increasing ventilation rates may impose energy costs and increase HVAC systems (Fisk 2017). It is important to note that there is likely a rate of diminishing returns for increasing ventilation rates and IAQ, and more outdoor air is not necessarily better. For example, one study did not find a difference in the rate of absence when comparing ventilation rates between 34 and 90 cfm/person (Myatt 2002). A recent study by the California Energy Commission (CEC) was conducted to determine the effectiveness of air change rates per hour in hospital settings as indicated by contaminant levels of CO2 and particulate concentrations. Testing various ventilation rates from 0 to 12 ACH, the study found that rates up to 2 ACH were effective in reducing CO2 and particulate concentrations in patient rooms, but there were diminishing rates of return for increasing rates above 2 ACH. In administrative areas, diminishing rates of return were observed above 0.5 ACH.

It is important to recognize that there are buildings that are currently under ventilated, and would benefit from increased ventilation. On the other hand, it is also important to acknowledge that some buildings are receiving adequate ventilation, and increasing the ventilation rate would not necessarily yield higher indoor air quality, yet would represent significant energy and cost implications. For example, current national standards for hospitals call for 4 ACH in patient rooms, and the CEC’s study suggests that increasing ventilation beyond that minimum standard does not positively impact IAQ, however, it would mean significantly increased energy use and costs associated with a higher ventilation rate (Barolin 2020).

IX. References

Review Articles

• Bernstein, Jonathan A., Neil Alexis, Hyacinth Bacchus, I. Leonard Bernstein, Pat Fritz, Elliot Horner, Ning Li et al. “The health effects of nonindustrial indoor air pollution.” Journal of Allergy and Clinical Immunology 121, no. 3 (2008): 585-591.
• Burge, P. S. “Sick building syndrome.” Occupational and environmental medicine 61, no. 2 (2004): 185-190.
• Cedeño-Laurent, J. G., A. Williams, P. MacNaughton, X. Cao, E. Eitland, J. Spengler, and J. Allen. “Building evidence for health: green buildings, current science, and future challenges.” Annual Review of Public Health 39 (2018): 291-308.
• Fisk, William J., Wanyu R. Chan, and Alexandra L. Johnson. “Does dampness and mold in schools affect health? Results of a meta‐analysis.” Indoor air 29, no. 6 (2019): 895-902.</li
• Fisk, William J. “The ventilation problem in schools: literature review.” Indoor Air 27, no. 6 (2017): 1039-1051.
• Fisk, William J., and Anibal T. De Almeida. “Sensor-based demand-controlled ventilation: a review.” Energy and buildings 29, no. 1 (1998): 35-45.
• Gerardi, Daniel A. “Building-related illness.” Clinical Pulmonary Medicine 17, no. 6 (2010): 276-281.
• Heerwagen, Judith. “Green buildings, organizational success and occupant productivity.” Building Research & Information 28, no. 5-6 (2000): 353-367.
• Laumbach, Robert J., and Howard M. Kipen. “Acute effects of motor vehicle traffic-related air pollution exposures on measures of oxidative stress in human airways.” Annals of the New York Academy of Sciences 1203 (2010): 107.
• Li, Yiping, Gabriel M. Leung, J. W. Tang, Xiaozhan Yang, C. Y. Chao, John Zhang Lin, J. W. Lu et al. “Role of ventilation in airborne transmission of infectious agents in the built environment-a multidisciplinary systematic review.” Indoor air 17, no. 1 (2007): 2-18.
• Lin, Xingbin, Josephine Lau, and Grenville K. Yuill. “Evaluation on the Validity of the Assumptions Underlying CO 2-Based Demand-Controlled Ventilation by a Literature Review.” ASHRAE Transactions 120, no. 1 (2014).
• OSHA (Occupational Safety and Health Administration. “Preventing Mold Related Problems in the Indoor Workplace.” US Department of Labor. (2006).
• Seppänen, O. A., W. J. Fisk, and M. J. Mendell. “Association of ventilation rates and CO2 concentrations with health andother responses in commercial and institutional buildings.” Indoor air 9, no. 4 (1999): 226-252.
• Sundell, Jan, Hal Levin, William W. Nazaroff, William S. Cain, William J. Fisk, David T. Grimsrud, F. Gyntelberg et al. “Ventilation rates and health: multidisciplinary review of the scientific literature.” Indoor air 21, no. 3 (2011): 191-204.
• Tarantini, Mariantonietta, Giovanni Pernigotto, and Andrea Gasparella. “A co-citation analysis on thermal comfort and productivity aspects in production and office buildings.” Buildings 7, no. 2 (2017): 36.
• Wallingford, K. M. “NIOSH Indoor Air Quality Investigations in Non-industrial Workplaces: An Update.” Internal NIOSH report. (1986).
• Wargocki, Pawel, David P. Wyon, and P. Ole Fanger. “Productivity is affected by the air quality in offices.” In Proceedings of Healthy Buildings, vol. 1, no. 1 (2000): 635-40.
• WSU Energy Program Report. “Measuring Carbon Dioxide Inside Buildings – Why is it Important?” Washington State University. (2013).

Primary Research

• Allen, Joseph G., Piers MacNaughton, Usha Satish, Suresh Santanam, Jose Vallarino, and John D. Spengler. “Associations of cognitive function scores with carbon dioxide, ventilation, and volatile organic compound exposures in office workers: a controlled exposure study of green and conventional office environments.” Environmental health perspectives 124, no. 6 (2016): 805-812.
• Apte, Michael G. “Associations between indoor CO2 concentrations and sick building syndrome symptoms in US office buildings: an analysis of the 1994-1996 BASE study data.” Indoor air 10, no. 4 (2000).
• Barolin, Austin, Travis English et al. “Advanced HVAC Technology Demonstration Project to Reduce Natural Gas Use in Hospitals.” California Energy Comission (2020).
• Bahnfleth, William, Lidia Morawska, Julian W. Tang, Philomena M. Bluyssen, Atze Boerstra, Giorgio Buonanno, Junji Cao et al. “How can airborne transmission of COVID-19 indoors be minimised?.” (2020).
• Fisk, William J., Seppanen, Olli, and David Faulkner. “Control of temperature for health and productivity in offices.” (2004).
• Gauderman, W. James, Edward Avol, Fred Lurmann, Nino Kuenzli, Frank Gilliland, John Peters, and Rob McConnell. “Childhood asthma and exposure to traffic and nitrogen dioxide.” Epidemiology (2005): 737-743.
• Kajtár, László, and Levente Herczeg. “Influence of carbon-dioxide concentration on human well-being and intensity of mental work.” QJ Hung. Meteorol. Serv 116 (2012): 145-169.
• Lanphear, Bruce P., C. Andrew Aligne, Peggy Auinger, Michael Weitzman, and Robert S. Byrd. “Residential exposures associated with asthma in US children.” Pediatrics 107, no. 3 (2001): 505-511.
• Laski, Jonathan. “Doing Right by Planet and People: The Business Case for Health and Wellbeing in Green Building.” World Green Building Council (2018).
• Maddalena, R., M. J. Mendell, K. Eliseeva, W. R. Chan, D. P. Sullivan, M. Russell, U. Satish, and W. J. Fisk. “Effects of ventilation rate per person and per floor area on perceived air quality, sick building syndrome symptoms, and decision‐making.” Indoor air 25, no. 4 (2015): 362-370.
• MacNaughton, Piers, James Pegues, Usha Satish, Suresh Santanam, John Spengler, and Joseph Allen. “Economic, environmental and health implications of enhanced ventilation in office buildings.” International journal of environmental research and public health 12, no. 11 (2015): 14709-14722.
• Mendell, Mark J., Quanhong Lei, M. G. Apte, and William J. Fisk. “Outdoor air ventilation and work-related symptoms in US office buildings-results from the BASE study.” (2005).
• Mendell, Mark J., Ekaterina A. Eliseeva, Molly M. Davies, Michael Spears, Agnes Lobscheid, William J. Fisk, and Michael G. Apte. “Association of classroom ventilation with reduced illness absence: a prospective study in California elementary schools.” Indoor air 23, no. 6 (2013): 515-528.
• Milton, Donald. “Risk of sick leave associated with outdoor air supply rate, humidification, and occupant complaints.” Indoor air 10 (2000): 212-221.
• Mumma, Stanley, Jeong, Jae-Weon, and William P. Bahnfleth. “Energy conservation benefits of a dedicated outdoor air system with parallel sensible cooling by ceiling radiant panels.” ASHRAE Transactions 109 (2003): 627.
• Myatt, Theodore A., John Staudenmayer, Kate Adams, Michael Walters, Stephen N. Rudnick, and Donald K. Milton. “A study of indoor carbon dioxide levels and sick leave among office workers.” Environmental Health 1, no. 1 (2002): 3.
• Nurmagambetov, Tursynbek, Robin Kuwahara, and Paul Garbe. “The economic burden of asthma in the United States, 2008–2013.” Annals of the American Thoracic Society 15, no. 3 (2018): 348-356.
• Roy, Angkana, Perry Sheffield, Kendrew Wong, and Leonardo Trasande. “The effects of outdoor air pollutants on the costs of pediatric asthma hospitalizations in the United States, 1999-2007.” Medical care 49, no. 9 (2011): 810.
• Shan, Xin, Jin Zhou, Victor W-C. Chang, and En-Hua Yang. “Comparing mixing and displacement ventilation in tutorial rooms: Students’ thermal comfort, sick building syndromes, and short-term performance.” Building and Environment 102 (2016): 128-137.
• Takaro, Tim K., James Krieger, Lin Song, Denise Sharify, and Nancy Beaudet. “The Breathe-Easy Home: the impact of asthma-friendly home construction on clinical outcomes and trigger exposure.” American Journal of Public Health 101, no. 1 (2011): 55-62.
• Vehviläinen, Tommi, Harri Lindholm, Hannu Rintamäki, Rauno Pääkkönen, Ari Hirvonen, Olli Niemi, and Juha Vinha. “High indoor CO2 concentrations in an office environment increases the transcutaneous CO2 level and sleepiness during cognitive e work.” Journal of occupational and environmental hygiene 13, no. 1 (2016): 19-29.
• Wargocki, Pawel, Jan Sundell, W. Bischof, G. Brundrett, Povl Ole Fanger, F. Gyntelberg, S. O. Hanssen et al. “Ventilation and health in non-industrial indoor environments: report from a European Multidisciplinary Scientific Consensus Meeting (EUROVEN).” Indoor air 12, no. 2 (2002): 113-128.
• Wyon, David P. “The effects of indoor air quality on performance and productivity.” Indoor air 14, no. 1 (2004): 92-101.

Other

• ANSI/ASHRAE 62.-2019. “Ventilation for Acceptable Indoor Air Quality.” American Society of Heating Refrigerating and Air-Conditioning Engineers. https://ashrae.iwrapper.com/ViewOnline/Standard_62.1-2019 (2020).
• EPA (Environmental Protection Agency). “Report on the Environment – Indoor Air Quality.” Environmental Protection Agency. https://www.epa.gov/report-environment/indoor-air-quality (2020).
• ESRL (Earth System Research Laboratories). National Oceanic and Atmospheric Administration https://www.esrl.noaa.gov/ (2020).
• WDHS (Wisconsin Department of Health Services). “Carbon Dioxide.” Wisconsin Department of Health Services. https://www.dhs.wisconsin.gov/chemical/carbondioxide.htm (2020).