Air Quality in Stamford, Connecticut — Live
Live readings from PurpleAir sensors across Stamford — with free alerts when Fairfield County's summer smog rolls in.
Live Stamford AQI from nearby PurpleAir sensors loads when this page opens in a browser, along with a live sensor map covering Stamford and Greenwich, Darien, New Canaan, Norwalk.
Stamford doesn't have a fire season, and most of the year the air here is unremarkable in a good way. The real story is summer smog: Fairfield County has posted the worst ozone grade in all of New England in the American Lung Association's last two annual reports, and that pollution mostly isn't made here — it drifts up the coast from the New York City metro area and gets trapped along the Connecticut shoreline on hot, humid afternoons. Stamford adds its own year-round wrinkle too, since I-95 runs directly through several city neighborhoods.
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.
Fairfield County keeps failing the ozone grade
The American Lung Association's 2025 State of the Air report gave Fairfield County an F for ozone pollution for the 2021–2023 period it covers, with an average of roughly 18 unhealthy ozone days a year — worse than any other county in New England, even after Cook County, Illinois took over the single worst national ranking the county had held before. Ruth Canovi, the Lung Association's Connecticut advocacy director, was blunt about what that shift actually means: "That's not because we've improved. That's because they worsened."
The county carries the health toll to match: over 81,000 adult asthma cases and more than 15,000 pediatric asthma cases in Fairfield County alone, according to the same report. Dr. David Hill, a pulmonary physician quoted in local coverage, put it simply — patients come in with more trouble breathing specifically "on hot and humid days," which is exactly when Stamford's ozone numbers are worst.
Why the smog collects here: New York City's plume and the Long Island Sound breeze
The mechanism has a name — LISTOS, the Long Island Sound Tropospheric Ozone Study, a multi-agency NASA/EPA/NESCAUM field campaign run in the summer of 2018 specifically because this stretch of coast kept posting stubbornly high ozone despite decades of nationwide air-quality progress. The cause: New York City's enormous concentration of emission sources — cars, trucks, ships, industrial boilers, power plants — forms a pollution plume that the cool waters of Long Island Sound then trap in a shallow, stable marine layer just offshore.
On hot afternoons, as the land heats up faster than the water, a sea breeze forms and carries that trapped plume inland — straight across the Connecticut shoreline, Stamford included. It's the geography working against the county: the same summer heat that makes ozone form in the first place is what pulls the polluted air off the Sound and over the towns sitting along it.
I-95 runs straight through the South End
Beyond the regional ozone story, Stamford has a pollution source of its own. I-95 cuts directly through six city neighborhoods, and no home in the South End sits more than a mile from the highway. Resident Sheila Barney told the Connecticut Mirror in 2024 that she gets air-quality alerts warning of a "bad day for breathing" specifically when highway congestion traps exhaust in the neighborhood — a corridor that runs through majority-minority, working-class communities that mid-century highway planners routed the interstate through in the first place.
The state opened a Planning and Environmental Linkages study on the corridor in 2022, looking at whether Stamford could follow cities like New Haven, Hartford, and Boston in reimagining a stretch of urban highway. Until that goes anywhere, the South End's daily exposure to highway pollution runs independently of — and often on top of — the county's summer ozone season.
Stamford air quality FAQ
What is the air quality in Stamford right now?
This page shows the current AQI for Stamford, 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.
Why does Stamford get smoggy in summer?
Fairfield County has posted the worst ozone grade in New England in the American Lung Association's recent State of the Air reports. The pollution mostly forms over New York City, gets trapped in a shallow marine layer over Long Island Sound, and then rides the afternoon sea breeze inland over the Connecticut shoreline — a pattern federal researchers studied directly in the 2018 LISTOS field campaign. Hot, humid, low-wind days are when Stamford's ozone numbers are worst.
Is I-95 a pollution problem for Stamford?
Yes, for neighborhoods close to it. I-95 runs directly through six Stamford neighborhoods, and no home in the South End is more than a mile from the highway. Residents there have described getting air-quality alerts on days when highway congestion traps exhaust locally, separate from the county's broader summer ozone pattern.
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.
Where does Canairy's Stamford data come from?
Readings come from PurpleAir's network of laser particle sensors across Stamford and surrounding towns, cross-referenced with government monitors and the Google Air Quality API. You can see every sensor behind your numbers on the live map - there's no black box.
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.