Indoor Exposure to Particulate Matter
Background
Particle pollution is a mixture of solids and liquid droplets found in the air. Particle size is an important factor in how exposure to particulate matter (PM) affects human health, with particles under 10 micrometers (PM10) – and especially fine particles under 2.5 micrometers (PM2.5) – of greatest concern. When inhaled, these tiny particles can penetrate deep into the lungs and may also enter the bloodstream.
Long-standing research links PM2.5 exposure to premature death and to a wide array of serious respiratory, cardiovascular, neurological, endocrine, and other health problems. People at increased risk of harm from exposure to particulate matter include children, older adults, pregnant people. Those who have underlying health conditions such as heart disease and lung diseases like asthma also face higher risk. Studies have documented racial disparities in the health burden of asthma, as well as disproportionate exposure to and health impacts of air pollution by race and socioeconomic status.
Because most people in the U.S. spend the large majority of their time inside buildings, much of our exposure to particulate matter occurs indoors. Both outdoor and indoor PM sources contribute to indoor exposure. Indoor activities that generate particle pollution include cooking, wood burning, and smoking. Particulate matter generated outdoors by sources such as vehicles, industrial facilities, and wildfires can penetrate the building envelope, and buildings vary widely in the level of protection they provide.
ELI Materials on Particulate Matter
Reducing Indoor Exposure to Particle Pollution from Outdoor Sources (2020)
Reducing Exposure to Cooking Pollutants: Policies and Practices to Improve Air Quality in Homes (2021)
Indoor Wood Burning: Policies to Reduce Emissions and Improve Public Health (2021)
Wildfire Smoke: State Policies for Reducing Indoor Exposure (2024)
The above reports describe state policies in effect as of the date of publication. ELI’s Database of State IAQ Laws, which is available in PDF format and through an online search tool, is updated periodically and also includes state policies related to indoor PM.
Opportunities for Policy Action
State policies and programs can improve public health significantly by implementing strategies for reducing indoor exposure to particulate matter. In addition to reducing ambient PM emissions, states can establish requirements and incentives for limiting emissions from indoor sources such as cooking and wood burning.
State policies are also needed for improving building filtration – a well-established technical solution for removing particulate matter from both the air entering a building and the air that is recirculated within a building. Because filtration can be provided through a building’s mechanical system or through portable air cleaning devices (commercial devices or DIY air cleaners), both new and existing buildings can be equipped with high efficiency filtration. States can thus incorporate filtration standards into building codes and into regulations governing the operation of schools and other facilities. Other technical solutions that can be advanced through state policy include siting buildings away from pollution sources and sealing building envelopes to reduce infiltration.
ELI research reports discuss these strategies in detail, highlighting leading state examples and key considerations for policymakers.
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