What is the air quality in Ontario CA?

Ontario CA, United States of America has an annual US AQI of 73 (Polluted) and average PM2.5 of 17.2 µg/m³, ranking #3401 of 5856 cities. Main pollutant: PM2.5.

What is the cleanest month in Ontario CA?

April is typically the cleanest month (AQI 61) and August the most polluted (AQI 91).

Where does Ontario CA's air quality data come from?

PM2.5: 1998–2026 (monitors 1999–2026, satellite 1998–2002, 2004–2011; 2026 provisional). Measured by government monitoring stations. Full sources are on the methodology page.

Ontario CA, United States of America — Air Quality & Clean City Guide 2026

Ontario CA Air Quality Data

Global rank	City	Continent	AQI	PM2.5
3401	Ontario CA, United States of America	North America	AQI 73	PM2.5 17.2 µg/m³