Where It Comes From
diesel and traffic exhaust, wood/coal burning, wildfires and agricultural burning, some industrial processes; indoors from candles, kerosene lamps, and solid-fuel stoves. [1][2]
How You Are Exposed
breathing outdoor air near busy roads or during smoke events; PM2.5 also infiltrates indoors; jobs using diesel equipment; commuting in heavy traffic; cooking/heating with solid fuels. [1][2]
Why It Matters
can trigger asthma and bronchitis, raise risks of heart attack, stroke, and premature death; outdoor air pollution/PM and diesel exhaust are carcinogenic. [1][2][3]
Who Is at Risk
children, older adults, people with heart or lung disease, pregnant people, workers around diesel exhaust, and residents near highways or solid-fuel use. [1][2]
How to Lower Your Exposure
check AQI; avoid or reroute from traffic; keep windows closed and use recirculation in cars on bad-air days; use MERV-13/HEPA filtration; wear a well-fitted N95 during smoke/high PM; limit indoor burning and maintain clean-burning appliances. [2][4]
References
- [1]U.S. EPA. Integrated Science Assessment for Particulate Matter (2022).
- [2]WHO. WHO Global Air Quality Guidelines: Particulate Matter (PM2.5 and PM10) (2021).
- [3]IARC. Outdoor Air Pollution and Particulate Matter are Carcinogenic to Humans (2013).
- [4]CDC. Protect Yourself from Wildfire Smoke (portable HEPA cleaners, masks) (accessed 2025).