City breathing reports
Live air quality for 20 major US cities, refreshed through the day from the Open-Meteo air quality model, plus the local triggers that actually affect how your city breathes: wildfire smoke, pollen seasons, winter inversions, and dust.
LA's basin geography traps vehicle exhaust and ozone against the San Gabriel Mountains, and late-summer wildfire smoke regularly pushes PM2.5 into unhealthy territory. Ozone peaks on hot, sunny afternoons inland (San Fernando Valley, Riverside side).
NYC's air is dominated by traffic and building emissions, with occasional spikes from Canadian wildfire smoke drifting down the Hudson Valley, as in the orange-sky episode of June 2023. Winter inversions can hold PM2.5 close to street level.
Chicago sits downwind of industrial corridors in northwest Indiana, and lake-breeze patterns can recirculate ozone along the shoreline on hot days. Ragweed season (August to October) adds a heavy allergy load.
Houston combines petrochemical plant emissions along the Ship Channel with intense humidity that makes heavy air feel heavier. It is consistently among the worst US metros for ozone.
Phoenix deals with desert dust (PM10), monsoon-season haboobs, and some of the highest ozone readings in the country during its long hot season. Winter temperature inversions trap wood smoke over the valley.
Philadelphia's air quality tracks the I-95 corridor's traffic density, with ozone alerts common in July and August. Tree pollen in April and May is among the worst on the East Coast.
San Antonio sits at the heart of Texas cedar fever country: mountain cedar pollen explodes from December through February and causes allergy symptoms many residents mistake for a winter cold. Saharan dust occasionally arrives in summer.
San Diego's coastal air is usually clean, but Santa Ana wind events reverse the flow, carrying inland smog and wildfire smoke to the coast. Fall fire season is the main PM2.5 risk.
The Dallas-Fort Worth metroplex has chronic summer ozone problems driven by heat and sprawling traffic. Spring brings heavy oak and grass pollen riding strong south winds.
Austin's signature breathing challenge is cedar fever: Ashe juniper pollen from the Hill Country peaks in January and can reach counts seen almost nowhere else on earth. Summer ozone and occasional Saharan dust add to the mix.
San Francisco's ocean air is typically excellent, but September and October wildfire smoke events can swing the city from the cleanest to the most polluted air in the country within a day, as in the orange-sky day of September 2020.
Seattle's maritime air is clean most of the year, but August and September wildfire smoke from the Cascades and British Columbia now routinely produces the city's worst air days. Damp winters also mean indoor mold is a common congestion trigger.
Denver's 'brown cloud' forms when winter temperature inversions trap pollution against the Front Range. Summer brings ozone alerts and smoke from western wildfires, all at a mile-high altitude where the air is already 17% thinner.
Miami's breathing challenges are humidity, year-round mold spores, and Saharan dust plumes that cross the Atlantic each summer, tinting skies and elevating PM10. Ocean breezes keep ozone relatively low.
Atlanta's spring pollen is legendary: pine pollen coats the city yellow each April while oak and birch drive allergy counts over 1,000 grains per cubic meter. Summer heat plus sprawl traffic creates frequent ozone alerts.
Boston's coastal location keeps air relatively clean, but spring birch and oak pollen hit hard, and winter nor'easter pressure swings are a classic sinus-pressure trigger for residents.
Minneapolis endures some of the coldest, driest winter air in urban America, which irritates airways on its own, and now sees summer smoke from Canadian boreal forest fires almost annually. Ragweed season runs late August into October.
Las Vegas valley air carries desert dust, high summer ozone, and extremely low humidity that dries out nasal passages. Winter inversions trap particulates between the surrounding mountain ranges.
Salt Lake City's winter inversions are among the most severe in the US: cold air pools in the valley and holds PM2.5 for days or weeks. Dust from the shrinking Great Salt Lake lakebed is an emerging concern.
Portland's air is clean most of the year, but the 2020 wildfire season gave it the worst air quality of any major city on earth for several days. Grass pollen in the Willamette Valley each June is among the highest recorded anywhere.
Sacramento sits in the Central Valley bowl where wildfire smoke, agricultural dust, and vehicle exhaust accumulate. Its long fire season and valley geography make it one of California's most smoke-affected capitals.