Browse our Air Pollutants guide to discover PM2.5, PM10, ozone, and nitrogen dioxide, where they come from, and how each one affects your air quality.
Pollutants that affect AQI the most are PM2.5 and PM10 (fine particles).Other major contributors include ozone (O₃), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and carbon monoxide (CO), all of which can harm human…
It is safe when PM2.5 levels are low, but it becomes unhealthy when concentrations are high, as fine particles can enter the lungs and affect breathing and heart health. When people talk about…