Air Quality in Stamford, Connecticut — Live
Live readings from PurpleAir sensors across Stamford — with free alerts when Fairfield County's summer smog rolls in.
AQI 17 from 2 PurpleAir sensors · Trending up · data from PurpleAir
As of , the air quality in Stamford, Connecticut is AQI 17 — Good and rising — with PM2.5 at 3.0 µg/m³, the median of 2 live PurpleAir sensors reading 8 to 26. Canairy's verdict: Breathe easy.
For scale, that PM2.5 reading is below the World Health Organization's 24-hour guideline of 15 µg/m³. The WHO figure is a daily average and this is a live reading, so read it as a sense of magnitude rather than a formal exceedance — a brief spike and a bad day are not the same thing. More on the WHO guidelines
Pollen today in Stamford: weeds pollen is the strongest of the three at a high level, from Google's pollen forecast. Canairy shows the tree, grass and weed forecast beside the air reading on every plan, including the free one.
Free to download · Live data from PurpleAir & public monitors
Live PurpleAir sensor map for Stamford and Greenwich, Darien, New Canaan, Norwalk. Every dot is a real sensor, color-coded by current air quality.
Sensor by sensor in Stamford
The sensors Canairy reads in Stamford agree right now — all 2 sit in the Good band, a 18-point spread — so the city-wide number is a fair description of the whole area today.
| From city center | AQI | Category |
|---|---|---|
| 0.9 mi E | 8 | Good |
| 5.4 mi NW | 26 | Good |
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.
What Canairy does for Stamford
A clear verdict
Not just a number — a plain-English call for Stamford: open the windows, or keep them shut.
Smoke alerts
A push or text the moment the air crosses your threshold — and again when it clears.
A heads-up before it's bad
Trend alerts catch the air turning, so you can close up the house before the smoke settles in.
Every place you care about
Home, work, the kids' school — across Stamford or across the country, on one screen.
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?
As of September 14, 2026 at 8:09 AM EDT, the air quality in Stamford, Connecticut is AQI 17 — Good — with PM2.5 at 3.0 µg/m³, the median of 2 live PurpleAir sensors. Open the windows. Great for outdoor activity.
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 the AQI numbers mean
| AQI | Category | What it means for you |
|---|---|---|
| 0–50 | Good | Open the windows. Great for outdoor activity. |
| 51–100 | Moderate | Sensitive groups may want to take it slower outside. |
| 101–150 | Unhealthy for Sensitive Groups | Kids, elderly, and respiratory conditions stay closer to home. |
| 151–200 | Unhealthy | Skip outdoor exercise. Close windows. |
| 201–300 | Very Unhealthy | Limit time outside. N95 if you must go. |
| 301+ | Hazardous | Health emergency. Stay inside, run filtration if you have it. |
Canairy lets you tighten these bands if you’re more sensitive than the EPA default, so an alert can fire before the official category changes. How to read the Air Quality Index
Where these readings come from
The AQI at the top of this page is the median of the 2 curated PurpleAir sensors Canairy tracks in and around Stamford, with outliers set aside so that one sensor brought indoors — or parked beside a barbecue — cannot set the number for a whole city. Every sensor behind it is listed above with its distance and bearing from the city center. There is no black box here.
In the app, a place you save resolves the same way first. When no neighborhood sensor is reporting it falls back to the nearest EPA AirNow monitor, and anything modeled rather than measured is labelled a regional estimate rather than passed off as a sensor reading. How low-cost sensors compare to regulatory monitors
About Canairy
Canairy is free to download. The free plan covers one saved place with live readings, a plain-English verdict, and push alerts when the air crosses a threshold you choose. Paid plans add more places, faster refreshes, and SMS alerts. It is built by two parents in Sonoma County, California, who got tired of guessing whether it was safe to send the kids outside. Why we built it
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Air quality near Stamford
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