Metro area air quality · 2025

Decatur, AL

Median AQI 42 (Good). 81.1% of monitored days rated Good across this metro's EPA monitoring network.

42
Median AQI
81.1%
Good-air days
0
Unhealthy days
67%
Cleaner than US metros

Aggregated from EPA Air Quality System (2025), 243 monitored days. EPA AQS →

The verdict

The Decatur, AL metro runs good on the EPA scale, cleaner than the median US metro, a median AQI of 42 with 81.1% of 243 monitored days in the Good band.

42
median AQI · Good
81.1%
days rated Good
67%
cleaner than US metros
71
worst single reading

No day crossed into the Unhealthy tier across the metro's monitors in 2025.

Insights: Decatur, AL metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 42 over 243 measured days in 2025, which corresponds to a Good band and a Good metro-wide health grade. The monitored-day split lands at 197 Good days (81%), 46 Moderate (19%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 54 while the highest single-day reading hit 71 (Moderate). Metro residents averaged roughly 24.3 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, good days shifted by -55 and the median AQI moved +1 points, which classifies the multi-year trajectory as improving. The metro avoided any Unhealthy-tier days entirely, an outcome that typically reflects favorable wind patterns, lower industrial density, or effective regional emission controls. Metros with comparable AQI profiles include Albany-Schenectady-Troy, NY (66.3% good, AQI 42); Bismarck, ND (75.8% good, AQI 42); Bloomington, IN (70.1% good, AQI 42).

Air Quality Summary

Median AQI

42

Good

Good Days

81.1%

197 of 243 days

Max AQI

71

Moderate

Health Grade

Good

90th pct: 54

AQI Day Breakdown (2025)

Distribution of 243 monitored days across EPA AQI categories.

Good

197

81%

Moderate

46

19%

USG

0

0%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Good

The Decatur, AL metro area's air quality is rated Good based on 81.1% good air days. No unhealthy air days were recorded in 2025.

Air quality is generally acceptable. Unusually sensitive people should monitor real-time conditions at AirNow.gov during high-pollution events.

How does the Decatur, AL metro compare?

How Decatur, AL compares

Good-day share better than US avg
Decatur, AL 81.1%
Albany-Schenectady-Troy, NY 66.3%
US average 71.3%
Median AQI worse than US avg
Decatur, AL 42
Albany-Schenectady-Troy, NY 42
US average 41
Unhealthy days / yr better than US avg
Decatur, AL 0
Albany-Schenectady-Troy, NY 0
US average 1

5-Year Air Quality Trend

Air quality is improving in the Decatur, AL metro. Best year: 2024 (264 good days).

Year Good Moderate Unhealthy Median AQI
2020 252 105 0 41
2021 208 157 0 47
2022 208 156 0 47
2023 257 106 0 43
2024 264 102 0 44
2025 197 46 0 42

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Decatur, AL.

Albany-Schenectady-Troy, NY

AQI 42 · 66.3% good

42

Bismarck, ND

AQI 42 · 75.8% good

42

Bloomington, IN

AQI 42 · 70.1% good

42

Cape Coral-Fort Myers, FL

AQI 42 · 74.4% good

42

Daphne-Fairhope-Foley, AL

AQI 42 · 72.2% good

42

Deltona-Daytona Beach-Ormond Beach, FL

AQI 42 · 78.4% good

42

More Air Quality Data

Explore EPA air quality rankings and guides across U.S. metros and counties.

Cleanest Metro Areas

U.S. metros ranked by their share of Good air-quality days.

Worst Air Quality

Counties and metros with the most unhealthy air days.

All Metro Areas

Annual AQI by CBSA for every monitored U.S. metro area.

Best and Worst City Air

What drives urban air quality and how metro areas compare.

Air Quality Guides

Frequently Asked Questions

What is the air quality in the Decatur, AL metro area? ▼
The Decatur, AL metro area has a median Air Quality Index (AQI) of 42, rated "Good." 81.1% of monitored days (197 out of 243) had good air quality in 2025.
How many unhealthy air days does Decatur, AL have? ▼
In 2025, the Decatur, AL metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 71.
Is air quality in Decatur, AL getting better or worse? ▼
Air quality in the Decatur, AL metro is improving based on 5-year trends (2020-2025). Best year: 2024 with 264 good days. Worst year: 2025 with 197 good days.
What does AQI 42 mean for health? ▼
An AQI of 42 is "Good", air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.
What is the 90th percentile AQI for Decatur, AL? ▼
The 90th percentile AQI for the Decatur, AL metro area is 54, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 71 (Moderate).
How does Decatur, AL compare to other metro areas? ▼
The Decatur, AL metro has 81.1% good air days. Similar metros: Albany-Schenectady-Troy, NY (66.3% good), Bismarck, ND (75.8% good), Bloomington, IN (70.1% good).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset, 2020–2025. 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 files (metro-level) · 2020–2025

Every figure on PlainAir is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.