PM2.5
Science & Engineering abbreviation · Environmental
| Stands for | Particulate matter 2.5 micrometers or smaller |
|---|---|
| Categories | Science & Engineering |
PM2.5 stands for Particulate matter 2.5 micrometers or smaller, an environmental abbreviation.
Fine airborne particles with a diameter of 2.5 micrometers or less, about one thirtieth the width of a human hair, small enough to reach deep into the lungs and bloodstream. Sources include vehicle exhaust, power plants, wood burning, wildfires and chemical reactions of gases in the air.
Example: Wildfire smoke pushed PM2.5 levels above 200 micrograms per cubic meter, and schools kept students indoors.
Usage notes
PM2.5 is the air pollutant most strongly linked to premature death, contributing to millions of deaths worldwide each year from heart and lung disease. The WHO lowered its annual guideline to 5 micrograms per cubic meter in 2021, and the US EPA tightened its annual standard to 9 in 2024. Indoor air purifiers with HEPA filters remove most PM2.5.
Related abbreviations
More environmental abbreviations
- NDC – Nationally determined contribution
- NEPA – National Environmental Policy Act
- NOx – Nitrogen oxides
- NPDES – National Pollutant Discharge Elimination System
- ODS – Ozone-depleting substance
- PM10 – Particulate matter 10 micrometers or smaller
- RCP – Representative Concentration Pathway
- RCRA – Resource Conservation and Recovery Act
- REDD+ – Reducing emissions from deforestation and forest degradation
- SBTi – Science Based Targets initiative
- SDG – Sustainable Development Goal
- SLCP – Short-lived climate pollutant