Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
PM2.5 refers to fine particulate matter that is 2.5 micrometers or smaller in diameter, which can be found in the air we breathe and can have harmful effects on human health.
Related terms
Particulate Matter (PM10): Refers to even larger particles of dust, dirt, soot, and smoke that are 10 micrometers or smaller in diameter.
Air Quality Index (AQI): A measurement used to report daily air quality levels and provide information about potential health risks associated with different levels of pollution.
Respiratory Diseases: Conditions such as asthma, bronchitis, and lung cancer that can be caused or worsened by exposure to high levels of particulate matter in the air.