Metro area air quality · 2025
Chattanooga, TN-GA
Median AQI 49 (Good). 51.0% of monitored days rated Good across this metro's EPA monitoring network.
- 49
- Median AQI
- 51.0%
- Good-air days
- 2
- Unhealthy days
- 13%
- Cleaner than US metros
Chattanooga, TN-GA posted a 2025 median AQI of 49 (Good) with 51.0% Good days
According to the U.S. EPA Air Quality System, the Chattanooga, TN-GA CBSA recorded a median AQI of 49 across 365 monitored days in 2025, with 51.0% 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 Chattanooga, TN-GA CBSA's 51.0% Good-day share places it cleaner than 13% of US metros in 2025.
- Closest median-AQI peer
- Canton-Massillon, OH (53.1% Good, median AQI 49) is the closest nationwide median-AQI peer to Chattanooga, TN-GA.
- 2020–2025 Good-day shift
- Chattanooga, TN-GA's Good-day share moved -5.5 points from 2020 to 2025 (median AQI +3).
- Median AQI
- Median AQI: 49
Aggregated from EPA Air Quality System (2025), 365 monitored days. EPA AQS →
The verdict
Chattanooga, TN-GA lands in the lower Good-day tercile (51.0% Good), a thinner clean-air share than most CBSA peers here. On the EPA scale the metro runs good, among the more polluted US metros, with a median AQI of 49 and 51.0% of 365 monitored days in the Good band.
- 49
- median AQI · Good
- 51.0%
- days rated Good
- 13%
- cleaner than US metros
- 181
- 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
- Chattanooga, TN-GA metro's Good-day share rose from 42.7% to 51.4% between the 2024 and 2025 EPA annual releases, a change of +8.7 percentage points.
- Chattanooga, TN-GA metro's peak single-day AQI rose from 126 to 181 between the 2024 and 2025 EPA annual releases, a change of +55 points.
- Chattanooga, TN-GA metro's Unhealthy-category days rose from 0 to 2 between the 2024 and 2025 EPA annual releases, a change of +2 days.
- Chattanooga, TN-GA metro's median AQI fell from 52 to 49 between the 2024 and 2025 EPA annual releases, a change of -3 points.
Chattanooga, TN-GA lands in the lower Good-day tercile (51.0% Good), a thinner clean-air share than most CBSA peers here. Signature read: 51.0% 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 49 over 365 measured days in 2025 (Good / Moderate). The monitored-day split lands at 186 Good (51%), 174 Moderate (48%), and 3 Unhealthy-for-Sensitive-Groups (1%). The 90th-percentile AQI finished at 65; the highest single-day reading hit 181 (Unhealthy).
Across 2020–2025, Good-day share shifted -5.5 points and median AQI moved +3 (worsening). The annual record contains 2 days at Unhealthy or worse. Metros with comparable AQI profiles include Canton-Massillon, OH (53.1% good, AQI 49); Carlsbad-Artesia, NM (53.7% good, AQI 49); Kingsville, TX (51.7% good, AQI 49).
Air Quality Summary
Median AQI
49
Good
Good Days
51.0%
186 of 365 days
Max AQI
181
Unhealthy
Health Grade
Moderate
90th pct: 65
AQI Day Breakdown (2025)
Distribution of 365 monitored days across EPA AQI categories.
Good
186
51%
Moderate
174
48%
USG
3
1%
Unhealthy
2
1%
Very Unhealthy
0
0%
Hazardous
0
0%
Health Impact Assessment
The Chattanooga, TN-GA metro area's air quality is rated Moderate based on 51.0% good air days. There were 2 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 3 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
5-Year Air Quality Trend
Air quality is worsening in the Chattanooga, TN-GA metro. Highest Good-day share: 2020 (56.9%, 207 of 364 monitored days).
| Year | Good | Moderate | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|
| 2020 | 207 | 156 | 1 | 46 | 151 |
| 2021 | 157 | 192 | 0 | 52 | 110 |
| 2022 | 134 | 224 | 0 | 54 | 105 |
| 2023 | 128 | 232 | 0 | 54 | 145 |
| 2024 | 155 | 208 | 0 | 52 | 126 |
| 2025 | 186 | 174 | 2 | 49 | 181 |
Metros with a similar median AQI
CBSA peers nationwide whose annual median AQI sits near Chattanooga, TN-GA (49).
Canton-Massillon, OH
Median AQI 49 · 53.1% Good-day share
Carlsbad-Artesia, NM
Median AQI 49 · 53.7% Good-day share
Kingsville, TX
Median AQI 49 · 51.7% Good-day share
Laramie, WY
Median AQI 49 · 55.6% Good-day share
Miami, OK
Median AQI 49 · 53.7% Good-day share
New Orleans-Metairie, LA
Median AQI 49 · 51.8% Good-day share
Metros with similar unhealthy-day exposure
A second relationship type: metros whose unhealthy-or-worse day count is closest to Chattanooga, TN-GA'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
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
Fort Dodge, IA
2 unhealthy-or-worse days · median AQI 45
Frequently Asked Questions
How many unhealthy air days does Chattanooga, TN-GA have? ▼
What is the air quality in the Chattanooga, TN-GA metro area? ▼
Is air quality in Chattanooga, TN-GA getting better or worse? ▼
What does AQI 49 mean for health? ▼
How does Chattanooga, TN-GA compare to other metro areas? ▼
What is the 90th percentile AQI for Chattanooga, TN-GA? ▼
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Chattanooga, TN-GA, 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, Chattanooga, TN-GA · 2020–2025