What is the air quality trend in Ontario?

Over the past 15 days, Ontario had an average AQI of 48 based on station measurements. The worst day was 2026-08-04 with AQI 57.

How is Ontario air quality measured?

Air quality in Ontario is measured by ground-level monitoring stations that report PM2.5 and PM10 concentrations hourly. CERNS.IO aggregates readings from nearby stations and converts PM2.5 to the US EPA Air Quality Index (AQI) scale.

Air Quality History for Ontario, United States

Name: Ontario Air Quality History
Creator: CERNS.IO
License: https://creativecommons.org/licenses/by/4.0/

Historical PM2.5 and AQI trend from monitoring stations near Ontario, United States.

Current AQI
Moderate CAMS model

48 Hours 7 Days 14 Days 20 Days

CSV JSON

Air Quality Index Station

333h

PM2.5 Station

333h · 22 stations

Temperature GFS model

56pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	PM10 avg	Hours	Stations
2026-08-08	52	52–52	12.4 µg/m³	5.2	1h	22
2026-08-07	46	39–62	11.3 µg/m³	7.1	24h	22
2026-08-06	52	40–68	13.2 µg/m³	9.0	24h	22
2026-08-05	54	40–77	14.2 µg/m³	9.9	24h	22
2026-08-04	57	39–107	15.7 µg/m³	10.0	24h	22
2026-08-03	50	35–65	12.4 µg/m³	9.6	24h	21
2026-08-02	46	38–55	11.1 µg/m³	7.7	24h	21
2026-08-01	51	45–57	12.7 µg/m³	8.9	24h	22
2026-07-31	51	38–62	12.9 µg/m³	10.8	24h	21
2026-07-30	50	37–59	12.3 µg/m³	9.7	24h	21
2026-07-29	48	40–56	11.7 µg/m³	8.8	24h	22
2026-07-28	46	32–103	11.6 µg/m³	6.5	24h	22
2026-07-27	42	32–53	10.2 µg/m³	6.6	24h	23
2026-07-26	45	42–48	10.7 µg/m³	7.9	24h	23
2026-07-25	44	36–53	10.4 µg/m³	7.0	20h	24

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