Air Quality in Corona, California — Live

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

Live Corona AQI from nearby PurpleAir sensors loads when this page opens in a browser, along with a live sensor map covering Corona and Norco, Eastvale, Yorba Linda, Temescal Valley.

Corona sits at the east end of the Santa Ana Canyon, on the northeastern edge of the Santa Ana Mountains, about 45 miles southeast of Los Angeles. The canyon is the water gap where the Santa Ana River cuts between the Santa Ana Mountains and the Chino Hills, and it is the low doorway between coastal Orange County and inland Riverside County. Almost everything that moves between the two goes through it, including the 91 freeway. More than 280,000 vehicles a day use the 91 at the Orange and Riverside county line, and in the Southern California Association of Governments' 2024 congestion report the westbound 91 at Green River Road in Corona is the worst bottleneck in Riverside County and the seventh worst of any in the six-county region, with roughly 1.19 million hours of vehicle delay a year spread over 4.3 miles.

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.

One freeway, one canyon, and everything squeezed through both

Corona's traffic problem and its air problem are the same shape. The Santa Ana Canyon is narrow, and the 91 is the only continuous freeway through it, which is why a corridor that carries more than 280,000 vehicles a day collapses to a crawl twice a day at the county line. The SCAG analysis puts the westbound queue at Green River Road at 4.3 miles long and about 1.19 million annual hours of vehicle delay. Idling and stop-start driving are the worst possible way to burn fuel, and the pollution from it lands on the neighbourhoods immediately either side of the freeway rather than dispersing.

SCAG makes the connection itself in that report, noting that many of the region's bottlenecks sit next to communities already carrying a higher pollution burden, with higher rates of asthma. If you live in south Corona up against the hills, a mile or two from the freeway, your air can be meaningfully different from a house in Green River or along the Auto Center Drive corridor on the same afternoon. That is the case for reading a sensor near you rather than a citywide number.

The winds are named after the canyon next door

The Santa Ana winds take their name from Santa Ana Canyon, where they blow hardest, and the earliest documented use of the phrase is an 1871 item in the Anaheim Gazette. They are katabatic winds, meaning they flow downhill, driven by high pressure over the Great Basin and the upper Mojave. As the air descends it warms by roughly 5 degrees Fahrenheit per thousand feet and its relative humidity collapses, often below 10 percent. Speeds regularly exceed 40 miles an hour.

For air quality this cuts both ways. A Santa Ana event scours the basin's smog out toward the ocean, so the sky can look startlingly clear. But the same wind lifts dust off bare ground and carries smoke a long way in a hurry, and it is what turns a roadside spark into a disaster. Corona knows what that looks like. On the morning of 15 November 2008, hot debris from a vehicle's catalytic converter started a fire beside the 91 in Corona. It merged with a second fire at the Olinda landfill and became the Freeway Complex Fire, which burned 30,305 acres across Orange and Riverside counties, destroyed 314 homes along with 43 outbuildings and four commercial buildings, forced roughly 40,000 people out of their houses, and closed the 91, the 71, the 57 and the 241.

Corona air quality FAQ

Why is there smoke in Corona today?

Check the wind first. If it is a hot, dry, windy day with the wind coming from the north or east, a fire anywhere in the Chino Hills or the Santa Ana Mountains can put smoke over Corona within an hour, because Santa Ana winds regularly exceed 40 miles an hour and carry smoke a long way fast. The Freeway Complex Fire in November 2008 started beside the 91 here on exactly that kind of day and burned 30,305 acres. If instead the air is hazy and still on a hot summer afternoon with no wind and no smell of smoke, it is more likely to be the regional smog layer working its way inland rather than a fire.

What is the air quality in Corona right now?

This page shows the current AQI for Corona, calculated from PurpleAir sensors across the city and updated continuously. The map below shows every sensor behind the number. Corona is spread out along a canyon with a freeway down the middle of it, so the reading at Green River can differ from one in south Corona against the foothills. Pick the sensor closest to where you actually spend your time.

Is it worse to live near the 91?

The 91 through Corona carries more than 280,000 vehicles a day at the county line, and the westbound approach to Green River Road is the worst traffic bottleneck in Riverside County by annual hours of delay. Vehicle pollution is concentrated close to the road and drops off sharply with distance, so a home a few hundred metres from the freeway is in a different situation from one a mile up into the hills. If you are near it, the practical steps are keeping windows on the freeway side shut during the morning and evening peaks and running a filter in the room where you sleep.

Do the Santa Ana winds clean the air or make it worse?

Both, at different times. A strong Santa Ana pushes the basin's accumulated smog out toward the coast, which is why the mountains look unusually sharp on those days. But the same wind picks up dust from bare ground and construction sites, and it is the reason Southern California's most destructive fires happen in autumn rather than midsummer. The useful habit is not to assume a windy day is a clean day. Look at the actual reading.

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.