PM25PM10

PM2.5 and PM10 are common classifications of ambient particulate matter by particle size. PM2.5 consists of particles 2.5 micrometers in diameter or smaller; PM10 includes particles up to 10 micrometers, making PM2.5 a subset of PM10. The combined term PM25PM10 is often used informally to discuss both fractions.

Particle sources vary: coarse PM (PM10) arises mainly from mechanical processes such as road dust, construction, and mineral dust, while fine PM (PM2.5) mainly derives from combustion (vehicles, power plants, burning) and secondary atmospheric reactions. Natural events like wildfires and dust storms also contribute.

Health effects link PM exposure to respiratory and cardiovascular diseases and to mortality. PM2.5 is particularly hazardous because its small size allows deep penetration into the lungs and entry into the bloodstream. Vulnerable groups include children, the elderly, and people with preexisting conditions.

Concentrations are reported as micrograms per cubic meter (µg/m3). Monitoring networks measure daily and annual averages using gravimetric and continuous methods. Results feed air quality indices that communicate risk to the public and guide protective actions.

Standards for PM2.5 and PM10 vary by country and organization; agencies set different limits and update them over time. Health advisories and public dashboards translate concentrations into guidance, while strategies to reduce PM levels focus on reducing emissions from vehicles, industry, and burning, and on indoor filtration and public health messaging.