Is the Air Quality Good in Fairfield, Connecticut?
Mostly — air quality in Fairfield, Connecticut is fair, not pristine. The city earns a Grade of C (fair) on a 5-year median AQI of 46 (Good), with 95 unhealthy-air days over five years (about 19 per year). Healthy adults are fine most of the time, but sensitive groups should watch the daily forecast.
Who Can Safely Breathe the Air in Fairfield, Connecticut?
Healthy adults can continue normal outdoor activity in most weather, but should pay attention to AQI alerts during the worst pollution windows. People with asthma, heart disease, or pregnancy should reduce prolonged or intense outdoor exertion on flagged days, and consider running an indoor HEPA air cleaner during peak season. Because PM2.5 penetrates deep into the lungs and bloodstream, an N95 or KN95 mask provides meaningful protection on smoky or high-particulate days — surgical masks do not.
Across the past five years, this area has logged 95 days where AQI rose into the "Unhealthy for Sensitive Groups" range or worse — about 19 days per year. That is roughly typical for a U.S. metro, with most caution days clustered in summer (ozone) or wildfire season.
Fairfield, Connecticut Air Quality Snapshot
| Air Quality Grade | C60/100 |
| 5-Year Median AQI | 46 (Good) |
| Most Recent Median AQI (2023) | 46 (Good) |
| Dominant Pollutant | Fine Particulate Matter (PM2.5) |
| 10-Year Trend | Improving (-0.88 AQI/yr) |
| Unhealthy Days (last 5 yr) | 95 |
| National Rank (cleanest = #1) | #810 of 1,020 (79th most polluted percentile) |
| Connecticut Rank | #8 of 8 |
What Does the C Grade Mean?
Fairfield, Connecticut earns a C — air quality is fair, but not great. With a 5-year median AQI of 46, the city sees a meaningful number of "Moderate" days each year, when the EPA flags air as a concern for unusually sensitive people.
Fairfield, Connecticut's 5-year median AQI of 46 is 5 points above the national average of 41 — meaningfully more polluted than the typical U.S. metro tracked here. Within Connecticut, Fairfield, Connecticut runs more polluted than the state average of 41 — local sources or geography are concentrating pollution above the state's typical reading.
For context within Connecticut: Hartford, Connecticut currently holds the state's cleanest grade (B, AQI 42), while New Haven, Connecticut sits at the bottom (C, AQI 45).
What's in Fairfield, Connecticut's Air?
The dominant pollutant in Fairfield, Connecticut is Fine Particulate Matter (PM2.5). Fine particulate matter — particles less than 2.5 micrometers across — comes mostly from combustion: vehicle exhaust, wildfire smoke, residential wood burning, and industrial emissions. Because these particles are small enough to enter the bloodstream, PM2.5 is the pollutant most strongly linked to cardiovascular disease, respiratory illness, and premature death.
Days by Dominant Pollutant (2023)
| Pollutant | Days as Dominant | Share of Year |
|---|---|---|
| Fine Particulate Matter (PM2.5) | 206 | 56% |
| Ground-Level Ozone | 146 | 40% |
| Nitrogen Dioxide | 12 | 3% |
| Coarse Particulate Matter (PM10) | 1 | 0% |
Is the Air Getting Better or Worse?
Air quality in Fairfield, Connecticut has been improving over the past decade, with median AQI dropping by roughly 0.9 points per year. That is consistent with the broader national pattern — most U.S. metros have seen steady reductions in particulate and ozone pollution since the 2010s as cleaner vehicles and power plants come online.
In 2014, Fairfield, Connecticut posted a median AQI of 53. By 2023 that figure was 46 — a drop of 7 AQI points cleaner across 10 years of EPA records.
Year-by-Year AQI in Fairfield, Connecticut
| Year | Median AQI | Good Days | Unhealthy Days | Dominant Pollutant |
|---|---|---|---|---|
| 2014 | 53 | 151 | 14 | PM2.5 |
| 2015 | 53 | 152 | 30 | PM2.5 |
| 2016 | 52 | 160 | 23 | PM2.5 |
| 2017 | 46 | 208 | 16 | PM2.5 |
| 2018 | 46 | 218 | 21 | PM2.5 |
| 2019 | 46 | 221 | 21 | PM2.5 |
| 2020 | 47 | 217 | 13 | PM2.5 |
| 2021 | 46 | 225 | 19 | PM2.5 |
| 2022 | 45 | 223 | 22 | PM2.5 |
| 2023 | 46 | 210 | 20 | PM2.5 |
How This Grade Is Calculated
The AirHistory Air Quality Grade combines four signals: the 5-year median AQI (40% of the score), the 10-year trend direction (30%), the count of unhealthy days per year (20%), and the dominant pollutant type (10%). All four come directly from the EPA Air Quality System (AQS), which aggregates readings from federally certified monitors. Read the full methodology.
More about Fairfield, Connecticut
Fairfield, Connecticut has an Air Quality Grade of C (fair) with a 5-year median AQI of 46. The dominant pollutant is Fine Particulate Matter (PM2.5), and air quality has been improving over the past decade.
The data source behind this answer is the EPA Air Quality System (AQS). Every figure on the page traces back to that source; the methodology page describes the inputs and the refresh cadence in full detail.
A practical caveat: the headline answer above reflects the most recent the EPA Air Quality System (AQS) vintage; underlying data is often revised for months after first publication, and the right reference for any specific decision is whichever vintage is current at the time of the decision. The as-of date is stamped on every page.
Source: EPA Outdoor Air Quality Data, 2026.