Air Quality in Ontario, California — Live

Live readings from PurpleAir sensors across Ontario — with free alerts the moment the air turns.

Live Ontario AQI from nearby PurpleAir sensors loads when this page opens in a browser, along with a live sensor map covering Ontario and Upland, Montclair, Rancho Cucamonga, Chino.

Ontario is where a lot of the country's freight changes vehicles. Ontario International Airport is the eighth-busiest airport in the United States by cargo tonnage, moving 835,129 tons in 2024, and it runs around the clock as the West Coast hub for UPS Airlines, a major FedEx Express point, and a focus city for Amazon Air. Interstates 10 and 15 and State Route 60 all cross inside the city. Most of Southern California's air conversation is about ozone, and Ontario gets its share of that — but the traffic moving through is its own distinct story.

Canairy watches the sensors around your home, your kids' school, and everywhere else you care about, and tells you in plain English when the air changes enough to matter.

An airport that never really stops

Ontario International sits about two miles east of downtown, with two parallel runways of 12,197 and 10,200 feet. Unlike most Southern California airports it is permitted to operate twenty-four hours a day, with procedural restrictions between 10pm and 7am rather than a curfew, and comparatively few noise-abatement rules — residents in the cities west of the field have complained about it for years, and nighttime procedures send departing aircraft east instead. Cargo is still growing: more than 428,000 tons moved through in the first half of 2026, up 7.6 percent year over year.

The airport is only one piece of it. Ontario has one of the largest concentrations of warehouse space in the greater Los Angeles region, and the Ontario Ranch area in the south of the city — rezoned from farmland in 1999 — has absorbed much of the recent build-out. Warehouses of 100,000 square feet or more fall under the regional air district's warehouse rule, which requires operators to earn credit for emission-reducing actions or pay a mitigation fee.

Ontario still gets the regional smog on top of everything else

Being closer to Los Angeles does not exempt Ontario from the ozone problem — it just means the city sits mid-stream rather than against the mountain wall. The sea breeze carries coastal emissions east all day, sunlight converts them to ozone in transit, and the mountains ringing the basin keep the whole mass from escaping. San Bernardino County, which includes Ontario, ranked first in the nation for ozone in the American Lung Association's 2026 State of the Air report with 159.2 weighted unhealthy days, and seventh for year-round particle pollution.

This year has been worse than usual. The basin recorded 39 days above the federal ozone standard in the first five months of 2026, the highest count in more than a decade, which the air district attributed to an unusually early stretch of heat following California's warmest March on record. Ozone is close to invisible, so a hazy afternoon with no fire anywhere nearby is usually this rather than smoke.

Ontario air quality FAQ

Why is there smoke in Ontario today?

Ontario is rarely the fire; it is usually downwind or downslope of one. Fires in the San Bernardino National Forest and the Cajon Pass to the northeast put smoke into the valley — the Blue Cut Fire burned roughly 37,000 acres in the pass in August 2016 and triggered a valley-wide smoke advisory, and the Line Fire near Highland in September 2024 pushed monitors in that direction from moderate to hazardous. Smoke also arrives from the west when the winds shift. On a hot summer afternoon, brown haze with no fire nearby is usually ozone.

What is the air quality in Ontario right now?

This page shows the current AQI for Ontario, calculated from PurpleAir sensors across the city and updated continuously. The map below shows every live sensor, so you can check the reading closest to your own neighborhood — a spot beside the 60 and a residential block off Euclid will not always agree.

Does the airport affect the air where I live?

Ontario International operates around the clock, is the eighth-busiest US airport by cargo, and its traffic is still growing. Aircraft and the truck traffic that feeds them both emit particles and nitrogen oxides. What that means at a specific address depends on how far away you are and which way the wind is blowing, which no citywide number can tell you — that is what the sensor map below is for.

When is Ontario's air worst?

Ozone peaks on hot, still summer afternoons, and the air district issues advisories during heat waves. Fine particle pollution follows a different pattern — worse in cool stagnant weather, during wildfires, and around the Fourth of July.

What AQI level is unhealthy?

Under the US EPA scale, AQI 0–50 is Good and 51–100 is Moderate. From 101 the air is Unhealthy for Sensitive Groups — kids, older adults, and people with asthma or heart conditions — and above 150 it's Unhealthy for everyone. Canairy translates these numbers into a plain-English verdict, like whether to close the windows or move a workout indoors.

Is Canairy free?

Yes. The Canairy app is free to download and includes live air quality for all your saved places, plain-English verdicts, and free push alerts when the air crosses your threshold. A paid plan adds extras like SMS text alerts.

Get Canairy free on Google Play.