Indoor Air Filters
Most air filters or purifiers remove particulate air pollutants, including dust, small particles, pollen, allergens, animal dander, and fibers. Some filters can remove gases such as SO2 and VOCs, though these are uncommon. When designed and used appropriately, air filters can be effective, especially since people spend most of their time indoors (1) and since filters reduce exposure to indoor sources of air pollution (e.g., cooking, smoking, vacuuming) and outdoor sources (e.g., traffic, power plants). We estimate that installing filters in Detroit area homes would reduce the number of outdoor PM2.5-related asthma exacerbations (defined using cough) by about 33,000 each year and avoid other adverse health impacts among both children and adults, including more than 100 hospitalizations for respiratory and cardiovascular disease and 140 premature mortalities, which primarily occur among older adults; installing filters in all schools would avoid about 12,000 asthma exacerbations among children.(2) Two recent program have used filters in Detroit. As part of a negotiated Supplemental Environmental Project (SEP) to resolve air quality violations,(3)(4) AK Steel agreed in 2015 to install air filters in the Salina Elementary and Intermediate Schools. In 2012-13, a study placing air filters in the homes of children with asthma showed dramatic reductions in particle concentrations.(5) Applicable filter strategies include expanding use of higher performance filters (MERV 11 and above) in homes, schools and commercial buildings; prioritizing buildings near major roads, construction sites, and other air pollution sources; creating multi-stakeholder “Air Filter Management Programs” and/or “Filter Committees” for schools; supporting businesses to upgrade ventilation and filter systems; increasing awareness of tax credits for green building, which includes indoor filtration systems; using certification systems to encourage green buildings and improved air quality; creating and using regular maintenance schedules for filter replacement and improving preventative maintenance in schools, homes and commercial spaces; expanding awareness and use of EPA’s Indoor Air Quality Tools for Schools;(6) encouraging Detroit and other municipalities to pass ordinances stipulating that schools adopt and implement an air quality and preventative maintenance programs; and using Community-Benefits Agreements to expand the use of filters, especially in buildings near emission sources.
1. Klepeis NE, Nelson WC, Ott WR, Robinson JP, Tsang AM, Switzer P, et al. 2001. The National Human Activity Pattern Survey (NHAPS): a resource for assessing exposure to environmental pollutants. Journal of exposure analysis and environmental epidemiology 11:231-52.
2. These health benefit estimates assume a “no-threshold” relationship between exposure and health outcomes, that is, there is no level of exposure below which adverse health outcome do not occur.
3. The United States Department of Justice. 2015. United States of America and the Michigan Department of Environmental Quality v. AK Steel Corporation. Available: http://www.justice.gov/sites/default/files/enrd/pages/attachments/2015/05/19/env_enforcement-2523241-v1 ak_steel_lodged_decree.pdf [accessed 11 February 2016].
4. The Detroit News. 2015. AK Steel to pay $1.35M fine, install filters at schools. Available: http://www.detroitnews.com/story/business/2015/05/20/ak-steel-fine-install-filters-schools/27658285/ [accessed 11 February 2016].
5. Du L, Batterman S, Parker E, Godwin C, Chin JY, O’Toole A, et al. 2011. Particle concentrations and effectiveness of free-standing air filters in bedrooms of children with asthma in Detroit, Michigan. Building and Environment 46: 2303-2313.
6. EPA (Environmental Protection Agency). Indoor Air Quality Tools for Schools Action Kit. Available: http://www.epa.gov/iaq-schools/indoor-air-quality-tools-schools-action-kit [accessed 2 March 2016]
Kristina Rice, Project Manager
Community Action to Promote Healthy Environments
University of Michigan School of Public Health
1415 Washington Heights
Ann Arbor, MI 48109-2029