Median AQI
45
Good
Tennessee · County air quality · 2025
Shelby County, Tennessee
Median AQI 45 (Good). 64.3% of monitored days rated Good, direct from EPA Air Quality System stations.
- 45
- Median AQI
- 64.3%
- Good-air days
- 0
- Unhealthy days
- 21%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Shelby County's air is good on balance, among the more polluted 10% of US counties, a median AQI of 45 with 64.3% of 182 monitored days in the Good band, driven mainly by Ozone.
- 45
- median AQI · Good
- 64.3%
- days rated Good
- Ozone
- main pollutant
- 21%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 90.
Data updated July 2026
- Good · 117 d · 64.3%
- Moderate · 65 d · 35.7%
How did Shelby County's air break down in 2025?
Across 182 monitored days, 117 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 90 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 182 days monitored. Median AQI: 45 (Good).
Insights: Shelby County, Tennessee. EPA monitors recorded a median Air Quality Index of 45 across 182 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 117 (64%) fell in the Good band (AQI 0–50), 65 (36%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 61, while the worst single-day peak hit 90 (Moderate). Residents averaged about 19.3 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (103 days), PM2.5 (76 days), PM10 (2 days), CO (1 days). Across the 2020–2025 trend window, good days shifted by -41 and the median AQI moved -7 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 90, moderate but never Unhealthy. Nearby counties show comparable readings: Anderson (91.0% good, AQI 42); Blount (69.6% good, AQI 46); Claiborne (96.3% good, AQI 36); Davidson (51.8% good, AQI 50); DeKalb (95.4% good, AQI 35); Dyer (79.4% good, AQI 34).
Air Quality Summary
Good Days
64.3%
117 of 182 monitored days
-10.7pp vs 75% target
Max AQI Recorded
90
Moderate
Health Grade
Moderate
90th-pct AQI 61
Shelby County, Good days share 64.3%
National avg
Share of monitored days at AQI 0-50 (Good band).
Shelby County, Unhealthy-or-worse share 0.0%
National avg
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
AQI Day Breakdown (2025)
Distribution of 182 monitored days across EPA AQI categories.
Good
117
64%
Moderate
65
36%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Shelby County.
- Ozone · 103 days · 56.6%
- PM2.5 · 76 days · 41.8%
- PM10 · 2 days · 1.1%
- CO · 1 days · 0.5%
Health Impact Assessment
Moderate
Shelby County's air quality is rated Moderate based on 64.3% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 64.3% of monitored days in 2025, with a median AQI of 45. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 103 of 182 monitored days.
5-Year Air Quality Trend
Air quality is improving in Shelby County. Best year: 2022 (224 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 158 | 207 | 0 | 1 | 52 | 153 |
| 2021 | 209 | 152 | 4 | 0 | 48 | 150 |
| 2022 | 224 | 131 | 8 | 2 | 46 | 159 |
| 2023 | 155 | 201 | 9 | 0 | 52 | 140 |
| 2024 | 126 | 231 | 6 | 3 | 55 | 159 |
| 2025 | 117 | 65 | 0 | 0 | 45 | 90 |
How does Shelby County compare?
How Shelby County compares
Good-day share worse than US avg
Shelby County 64.3%
Anderson County, Tennessee 91.0%
US average 76.5%
Median AQI worse than US avg
Shelby County 45
Anderson County, Tennessee 42
US average 38
Unhealthy days / yr about average
Shelby County 0
Anderson County, Tennessee 0
US average 0
Other Counties in Tennessee
Air quality comparison for nearby counties in Tennessee.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Shelby County.
Adair County, Oklahoma
AQI 45 · 59.2% good
Allen County, Indiana
AQI 45 · 58.2% good
Atascosa County, Texas
AQI 45 · 58.0% good
Baker County, Florida
AQI 45 · 69.1% good
Carson City County, Nevada
AQI 45 · 79.3% good
Clinton County, Iowa
AQI 45 · 59.9% good
What Shelby County's air means for you
The air here stays in the breathable range year-round, with Ozone the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-Ozone days, the guide explains what a median of 45 means for exposure. Health guidance
- See how Shelby County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Shelby County with its Tennessee neighbours before drawing a conclusion about the region. All of Tennessee
Based on 182 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
More Air Quality Data
Air Quality Guides
Frequently Asked Questions
What is the air quality in Shelby County, Tennessee? ▼
Shelby County has a median Air Quality Index (AQI) of 45, rated "Good." 64.3% of monitored days (117 out of 182) had good air quality in 2025.
What is the main pollutant in Shelby County? ▼
The primary pollutant in Shelby County is Ozone (O3), which was the main AQI driver on 103 days (57% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Shelby County have? ▼
In 2025, Shelby County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 90.
Is the air quality in Shelby County getting better or worse? ▼
Air quality in Shelby County is improving based on 5-year trends (2020-2025). Best year: 2022 with 224 good days. Worst year: 2025 with 117 good days.
What does AQI 45 mean for health? ▼
Shelby County's median AQI of 45 falls in the "Good" category. See the <a href="/guides/understanding-aqi" class="underline">AQI category guide</a> for what each range means for health.
How does Shelby County compare to other counties in Tennessee? ▼
Shelby County has 64.3% good air days. Nearby counties in Tennessee: Anderson (91.0% good), Blount (69.6% good), Claiborne (96.3% good), Davidson (51.8% good), DeKalb (95.4% good), Dyer (79.4% good).
What is the 90th percentile AQI in Shelby County? ▼
The 90th percentile AQI for Shelby County is 61, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 90 (Moderate).
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025 (aqs.epa.gov). For current conditions (not shown here — this page is historical annual data), see EPA AirNow (airnow.gov). See our methodology for how AQI, median, and coverage figures are computed.
Informational only, not professional advice. Data from EPA AQS. See our disclaimer.
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.