Metro area air quality · 2025
Hartford-West Hartford-East Hartford, CT
Median AQI 42 (Good). 66.6% of monitored days rated Good across this metro's EPA monitoring network.
- 42
- Median AQI
- 66.6%
- Good-air days
- 2
- Unhealthy days
- 38%
- Cleaner than US metros
Hartford-West Hartford-East Hartford, CT posted a 2025 median AQI of 42 (Good) with 66.6% Good days
According to the U.S. EPA Air Quality System, the Hartford-West Hartford-East Hartford, CT CBSA recorded a median AQI of 42 across 365 monitored days in 2025, with 66.6% 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 Hartford-West Hartford-East Hartford, CT CBSA's 66.6% Good-day share places it cleaner than 38% of US metros in 2025.
- Closest median-AQI peer
- Allentown-Bethlehem-Easton, PA-NJ (66.8% Good, median AQI 42) is the closest nationwide median-AQI peer to Hartford-West Hartford-East Hartford, CT.
- 2020–2025 Good-day shift
- Hartford-West Hartford-East Hartford, CT's Good-day share moved +1.0 points from 2020 to 2025 (median AQI -1).
- Median AQI
- Median AQI: 42
Aggregated from EPA Air Quality System (2025), 365 monitored days. EPA AQS →
The verdict
Hartford-West Hartford-East Hartford, CT's peak reading 164 is in the upper max-AQI tercile among CBSA metros here. On the EPA scale the metro runs good, more polluted than the median US metro, with a median AQI of 42 and 66.6% of 365 monitored days in the Good band.
- 42
- median AQI · Good
- 66.6%
- days rated Good
- 38%
- cleaner than US metros
- 164
- 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
- Hartford-West Hartford-East Hartford, CT metro's Good-day share fell from 77.1% to 68.3% between the 2024 and 2025 EPA annual releases, a change of -8.8 percentage points.
- Hartford-West Hartford-East Hartford, CT metro's peak single-day AQI fell from 185 to 164 between the 2024 and 2025 EPA annual releases, a change of -21 points.
- Hartford-West Hartford-East Hartford, CT metro's Unhealthy-category days rose from 1 to 2 between the 2024 and 2025 EPA annual releases, a change of +1 days.
Hartford-West Hartford-East Hartford, CT's peak reading 164 is in the upper max-AQI tercile among CBSA metros here. Signature read: peak AQI 164 (high tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 42 over 365 measured days in 2025 (Good / Moderate). The monitored-day split lands at 243 Good (67%), 111 Moderate (30%), and 9 Unhealthy-for-Sensitive-Groups (2%). The 90th-percentile AQI finished at 72; the highest single-day reading hit 164 (Unhealthy).
Across 2020–2025, Good-day share shifted +1.0 points and median AQI moved -1 (stable). The annual record contains 2 days at Unhealthy or worse. Metros with comparable AQI profiles include Allentown-Bethlehem-Easton, PA-NJ (66.8% good, AQI 42); Amarillo, TX (78.4% good, AQI 42); Carson City, NV (86.2% good, AQI 42).
Air Quality Summary
Median AQI
42
Good
Good Days
66.6%
243 of 365 days
Max AQI
164
Unhealthy
Health Grade
Moderate
90th pct: 72
AQI Day Breakdown (2025)
Distribution of 365 monitored days across EPA AQI categories.
Good
243
67%
Moderate
111
30%
USG
9
2%
Unhealthy
2
1%
Very Unhealthy
0
0%
Hazardous
0
0%
Health Impact Assessment
The Hartford-West Hartford-East Hartford, CT metro area's air quality is rated Moderate based on 66.6% good air days. There were 2 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 9 days reached "Unhealthy for Sensitive Groups" and peak AQI reached 164. Sensitive groups should monitor real-time conditions at AirNow.gov.
How does the Hartford-West Hartford-East Hartford, CT metro compare?
How Hartford-West Hartford-East Hartford, CT compares
5-Year Air Quality Trend
Air quality is stable in the Hartford-West Hartford-East Hartford, CT metro. Highest Good-day share: 2024 (77.1%, 276 of 358 monitored days).
| Year | Good | Moderate | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|
| 2020 | 245 | 119 | 0 | 43 | 129 |
| 2021 | 243 | 107 | 1 | 43 | 151 |
| 2022 | 251 | 107 | 0 | 43 | 147 |
| 2023 | 223 | 133 | 4 | 44 | 166 |
| 2024 | 276 | 81 | 1 | 40 | 185 |
| 2025 | 243 | 111 | 2 | 42 | 164 |
Metros with a similar median AQI
CBSA peers nationwide whose annual median AQI sits near Hartford-West Hartford-East Hartford, CT (42).
Allentown-Bethlehem-Easton, PA-NJ
Median AQI 42 · 66.8% Good-day share
Amarillo, TX
Median AQI 42 · 78.4% Good-day share
Carson City, NV
Median AQI 42 · 86.2% Good-day share
Casper, WY
Median AQI 42 · 86.3% Good-day share
Clarksville, TN-KY
Median AQI 42 · 72.0% Good-day share
Daphne-Fairhope-Foley, AL
Median AQI 42 · 75.5% Good-day share
Metros with similar unhealthy-day exposure
A second relationship type: metros whose unhealthy-or-worse day count is closest to Hartford-West Hartford-East Hartford, CT's 2 (independent of median AQI).
Ardmore, OK
2 unhealthy-or-worse days · median AQI 45
Bridgeport-Stamford-Norwalk, CT
2 unhealthy-or-worse days · median AQI 44
Chattanooga, TN-GA
2 unhealthy-or-worse days · median AQI 49
Cincinnati, OH-KY-IN
2 unhealthy-or-worse days · median AQI 56
Columbus, GA-AL
2 unhealthy-or-worse days · median AQI 48
Davenport-Moline-Rock Island, IA-IL
2 unhealthy-or-worse days · median AQI 46
Frequently Asked Questions
What is the 90th percentile AQI for Hartford-West Hartford-East Hartford, CT? ▼
How many unhealthy air days does Hartford-West Hartford-East Hartford, CT have? ▼
What is the air quality in the Hartford-West Hartford-East Hartford, CT metro area? ▼
Is air quality in Hartford-West Hartford-East Hartford, CT getting better or worse? ▼
What does AQI 42 mean for health? ▼
How does Hartford-West Hartford-East Hartford, CT compare to other metro areas? ▼
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Hartford-West Hartford-East Hartford, 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, Hartford-West Hartford-East Hartford, CT · 2020–2025