Metro area air quality · 2025

Bridgeport-Stamford-Norwalk, CT

Median AQI 44 (Good). 64.7% of monitored days rated Good across this metro's EPA monitoring network.

44
Median AQI
64.7%
Good-air days
2
Unhealthy days
33%
Cleaner than US metros

Bridgeport-Stamford-Norwalk, CT posted a 2025 median AQI of 44 (Good) with 64.7% Good days

According to the U.S. EPA Air Quality System, the Bridgeport-Stamford-Norwalk, CT CBSA recorded a median AQI of 44 across 365 monitored days in 2025, with 64.7% rated Good and 2 unhealthy or worse. This is an annual metro comparison, not a live advisory.

Data source EPA Air Quality System (AQS)

Cleaner than US metros
The Bridgeport-Stamford-Norwalk, CT CBSA's 64.7% Good-day share places it cleaner than 33% of US metros in 2025.
Closest median-AQI peer
Bartlesville, OK (68.0% Good, median AQI 44) is the closest nationwide median-AQI peer to Bridgeport-Stamford-Norwalk, CT.
2020–2025 Good-day shift
Bridgeport-Stamford-Norwalk, CT's Good-day share moved +6.9 points from 2020 to 2025 (median AQI -3).
Median AQI
Median AQI: 44

Aggregated from EPA Air Quality System (2025), 365 monitored days. EPA AQS →

The verdict

Bridgeport-Stamford-Norwalk, CT lands in the lower Good-day tercile (64.7% Good), a thinner clean-air share than most CBSA peers here. On the EPA scale the metro runs good, more polluted than the median US metro, with a median AQI of 44 and 64.7% of 365 monitored days in the Good band.

44
median AQI · Good
64.7%
days rated Good
33%
cleaner than US metros
174
worst single reading

2 days reached Unhealthy or worse across the metro's monitors in 2025.

Annual release change

What changed in the 2025 EPA annual release

2024 → 2025
  • Bridgeport-Stamford-Norwalk, CT metro's Good-day share fell from 71.3% to 68.2% between the 2024 and 2025 EPA annual releases, a change of -3.1 percentage points.
  • Bridgeport-Stamford-Norwalk, CT metro's peak single-day AQI rose from 154 to 174 between the 2024 and 2025 EPA annual releases, a change of +20 points.
  • Bridgeport-Stamford-Norwalk, CT metro's Unhealthy-category days fell from 3 to 2 between the 2024 and 2025 EPA annual releases, a change of -1 days.

Compared against 348 monitored days in 2024 and 346 in 2025. These are arithmetic differences between two stored EPA annual summaries, not a cause claim or a live advisory.

National release changes Two-year CSV

Bridgeport-Stamford-Norwalk, CT lands in the lower Good-day tercile (64.7% Good), a thinner clean-air share than most CBSA peers here. Signature read: 64.7% Good-day share (low tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 44 over 365 measured days in 2025 (Good / Moderate). The monitored-day split lands at 236 Good (65%), 108 Moderate (30%), and 19 Unhealthy-for-Sensitive-Groups (5%). The 90th-percentile AQI finished at 74; the highest single-day reading hit 174 (Unhealthy).

Across 2020–2025, Good-day share shifted +6.9 points and median AQI moved -3 (improving). The annual record contains 2 days at Unhealthy or worse. Metros with comparable AQI profiles include Bartlesville, OK (68.0% good, AQI 44); Berlin, NH-VT (81.5% good, AQI 44); Bloomington, IL (66.0% good, AQI 44).

Health effects of air pollution →

Air Quality Summary

Median AQI

44

Good

Good Days

64.7%

236 of 365 days

Max AQI

174

Unhealthy

Health Grade

Moderate

90th pct: 74

AQI Day Breakdown (2025)

Distribution of 365 monitored days across EPA AQI categories.

Good

236

65%

Moderate

108

30%

USG

19

5%

Unhealthy

2

1%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Moderate

The Bridgeport-Stamford-Norwalk, CT metro area's air quality is rated Moderate based on 64.7% good air days. There were 2 unhealthy days in 2025 when outdoor activity should be limited.

Air quality is acceptable most days, but 19 days reached "Unhealthy for Sensitive Groups" and peak AQI reached 174. Sensitive groups should monitor real-time conditions at AirNow.gov.

How does the Bridgeport-Stamford-Norwalk, CT metro compare?

How Bridgeport-Stamford-Norwalk, CT compares

Good-day share worse than typical
Bridgeport-Stamford-Norwalk, CT 64.7%
Bartlesville, OK 68.0%
Typical US metro 70.6%
Median AQI worse than typical
Bridgeport-Stamford-Norwalk, CT 44
Bartlesville, OK 44
Typical US metro 41
Unhealthy days / yr worse than typical
Bridgeport-Stamford-Norwalk, CT 2
Bartlesville, OK 1
Typical US metro 1

5-Year Air Quality Trend

Air quality is improving in the Bridgeport-Stamford-Norwalk, CT metro. Highest Good-day share: 2024 (71.3%, 248 of 348 monitored days).

Year Good Moderate Unhealthy Median AQI
2020 217 136 1 47
2021 225 119 6 46
2022 223 120 2 45
2023 210 135 7 46
2024 248 97 3 42
2025 236 108 2 44

Metros with a similar median AQI

CBSA peers nationwide whose annual median AQI sits near Bridgeport-Stamford-Norwalk, CT (44).

Bartlesville, OK

Median AQI 44 · 68.0% Good-day share

44

Berlin, NH-VT

Median AQI 44 · 81.5% Good-day share

44

Bloomington, IL

Median AQI 44 · 66.0% Good-day share

44

Boston-Cambridge-Newton, MA-NH

Median AQI 44 · 71.0% Good-day share

44

Buffalo-Cheektowaga-Niagara Falls, NY

Median AQI 44 · 63.8% Good-day share

44

Cedar City, UT

Median AQI 44 · 74.7% Good-day share

44

Metros with similar unhealthy-day exposure

A second relationship type: metros whose unhealthy-or-worse day count is closest to Bridgeport-Stamford-Norwalk, CT's 2 (independent of median AQI).

Ardmore, OK

2 unhealthy-or-worse days · median AQI 45

45

Chattanooga, TN-GA

2 unhealthy-or-worse days · median AQI 49

49

Cincinnati, OH-KY-IN

2 unhealthy-or-worse days · median AQI 56

56

Columbus, GA-AL

2 unhealthy-or-worse days · median AQI 48

48

Davenport-Moline-Rock Island, IA-IL

2 unhealthy-or-worse days · median AQI 46

46

Fort Dodge, IA

2 unhealthy-or-worse days · median AQI 45

45

Frequently Asked Questions

How many unhealthy air days does Bridgeport-Stamford-Norwalk, CT have? ▼
In 2025, the Bridgeport-Stamford-Norwalk, CT metro area recorded 2 unhealthy air days (2 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 174.
What is the air quality in the Bridgeport-Stamford-Norwalk, CT metro area? ▼
The Bridgeport-Stamford-Norwalk, CT metro area has a median Air Quality Index (AQI) of 44, rated "Good." 64.7% of monitored days (236 out of 365) had good air quality in 2025.
Is air quality in Bridgeport-Stamford-Norwalk, CT getting better or worse? ▼
Air quality in the Bridgeport-Stamford-Norwalk, CT metro is improving across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2024 at 71.3% (248 of 348 days). Lowest qualifying Good-day share: 2023 at 59.7% (210 of 352 days).
What does AQI 44 mean for health? ▼
An AQI of 44 is "Good", air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.
How does Bridgeport-Stamford-Norwalk, CT compare to other metro areas? ▼
The Bridgeport-Stamford-Norwalk, CT metro has 64.7% good air days. Similar metros: Bartlesville, OK (68.0% good), Berlin, NH-VT (81.5% good), Bloomington, IL (66.0% good).
What is the 90th percentile AQI for Bridgeport-Stamford-Norwalk, CT? ▼
The 90th percentile AQI for the Bridgeport-Stamford-Norwalk, CT metro area is 74, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 174 (Unhealthy).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Bridgeport-Stamford-Norwalk, CT, 2025. See our methodology for how AQI, median, and coverage figures are computed.

Read our methodology , how this data is sourced, computed, and verified.

Source: U.S. EPA Air Quality System (AQS) Annual AQI by CBSA summary, Bridgeport-Stamford-Norwalk, CT · 2020–2025