Metro area air quality · 2025

Chattanooga, TN-GA

Median AQI 48 (Good). 53.9% of monitored days rated Good across this metro's EPA monitoring network.

48
Median AQI
53.9%
Good-air days
2
Unhealthy days
17%
Cleaner than US metros

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

The verdict

The Chattanooga, TN-GA metro runs good on the EPA scale, among the more polluted US metros, a median AQI of 48 with 53.9% of 243 monitored days in the Good band.

48
median AQI · Good
53.9%
days rated Good
17%
cleaner than US metros
181
worst single reading

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

Insights: Chattanooga, TN-GA metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 48 over 243 measured days in 2025, which corresponds to a Good band and a Moderate metro-wide health grade. The monitored-day split lands at 131 Good days (54%), 108 Moderate (44%), and 2 Unhealthy-for-Sensitive-Groups (1%). The 90th-percentile AQI finished at 65 while the highest single-day reading hit 181 (Unhealthy). Metro residents averaged roughly 16.2 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, good days shifted by -76 and the median AQI moved +2 points, which classifies the multi-year trajectory as stable. The metro recorded 2 unhealthy-or-worse days combined, on those days the EPA recommends that sensitive groups limit prolonged outdoor exertion, and many schools and athletic programs adjust outdoor activity accordingly. Metros with comparable AQI profiles include Brookings, SD (53.0% good, AQI 48); Charleston-North Charleston, SC (58.2% good, AQI 48); Columbia, SC (57.3% good, AQI 48).

Air Quality Summary

Median AQI

48

Good

Good Days

53.9%

131 of 243 days

Max AQI

181

Unhealthy

Health Grade

Moderate

90th pct: 65

AQI Day Breakdown (2025)

Distribution of 243 monitored days across EPA AQI categories.

Good

131

54%

Moderate

108

44%

USG

2

1%

Unhealthy

2

1%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Moderate

The Chattanooga, TN-GA metro area's air quality is rated Moderate based on 53.9% good air days. There were 2 unhealthy days in 2025 when outdoor activity should be limited.

Air quality is acceptable most days, but 2 days reached "Unhealthy for Sensitive Groups" and peak AQI reached 181. Sensitive groups should monitor real-time conditions at AirNow.gov.

How does the Chattanooga, TN-GA metro compare?

How Chattanooga, TN-GA compares

Good-day share worse than US avg
Chattanooga, TN-GA 53.9%
Brookings, SD 53.0%
US average 71.3%
Median AQI worse than US avg
Chattanooga, TN-GA 48
Brookings, SD 48
US average 41
Unhealthy days / yr worse than US avg
Chattanooga, TN-GA 2
Brookings, SD 1
US average 1

5-Year Air Quality Trend

Air quality is stable in the Chattanooga, TN-GA metro. Best year: 2020 (207 good days).

Year Good Moderate Unhealthy Median AQI
2020 207 156 1 46
2021 157 192 0 52
2022 134 224 0 54
2023 128 232 0 54
2024 155 208 0 52
2025 131 108 2 48

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Chattanooga, TN-GA.

Brookings, SD

AQI 48 · 53.0% good

48

Charleston-North Charleston, SC

AQI 48 · 58.2% good

48

Columbia, SC

AQI 48 · 57.3% good

48

Corsicana, TX

AQI 48 · 58.1% good

48

Dayton, OH

AQI 48 · 56.2% good

48

Flagstaff, AZ

AQI 48 · 62.5% good

48

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 Chattanooga, TN-GA metro area? ▼
The Chattanooga, TN-GA metro area has a median Air Quality Index (AQI) of 48, rated "Good." 53.9% of monitored days (131 out of 243) had good air quality in 2025.
How many unhealthy air days does Chattanooga, TN-GA have? ▼
In 2025, the Chattanooga, TN-GA metro area recorded 2 unhealthy air days (2 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 181.
Is air quality in Chattanooga, TN-GA getting better or worse? ▼
Air quality in the Chattanooga, TN-GA metro is stable based on 5-year trends (2020-2025). Best year: 2020 with 207 good days. Worst year: 2023 with 128 good days.
What does AQI 48 mean for health? ▼
An AQI of 48 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 Chattanooga, TN-GA? ▼
The 90th percentile AQI for the Chattanooga, TN-GA metro area is 65, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 181 (Unhealthy).
How does Chattanooga, TN-GA compare to other metro areas? ▼
The Chattanooga, TN-GA metro has 53.9% good air days. Similar metros: Brookings, SD (53.0% good), Charleston-North Charleston, SC (58.2% good), Columbia, SC (57.3% 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.