Air pollutant glossary

Plain-English explainers for every pollutant we track. Sources, health effects, WHO guidelines.

PM2.5
PM2.5 (Fine particulate matter)
PM10
PM10 (Coarse particulate matter)
O3
Ozone (O3) - Ground level
NO2
Nitrogen Dioxide (NO2)
SO2
Sulfur Dioxide (SO2)
CO
Carbon Monoxide (CO)