Median AQI
45
Good
Georgia · County air quality · 2025
Gwinnett County, Georgia
Median AQI 45 (Good). 64.5% of monitored days rated Good, direct from EPA Air Quality System stations.
- 45
- Median AQI
- 64.5%
- Good-air days
- 0
- Unhealthy days
- 22%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Gwinnett County's air is good on balance, among the more polluted 10% of US counties, a median AQI of 45 with 64.5% of 273 monitored days in the Good band, driven mainly by PM2.5.
- 45
- median AQI · Good
- 64.5%
- days rated Good
- PM2.5
- main pollutant
- 22%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 84.
Data updated July 2026
- Good · 176 d · 64.5%
- Moderate · 97 d · 35.5%
How did Gwinnett County's air break down in 2025?
Across 273 monitored days, 176 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 84 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 273 days monitored. Median AQI: 45 (Good).
Insights: Gwinnett County, Georgia. EPA monitors recorded a median Air Quality Index of 45 across 273 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 176 (64%) fell in the Good band (AQI 0–50), 97 (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 84 (Moderate). Residents averaged about 19.3 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (154 days), Ozone (119 days). Across the 2020–2025 trend window, good days shifted by -70 and the median AQI moved +2 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 84, moderate but never Unhealthy. Nearby counties show comparable readings: Bibb (49.5% good, AQI 51); Charlton (79.0% good, AQI 24); Chatham (66.7% good, AQI 44); Clarke (66.7% good, AQI 44); Clayton (53.1% good, AQI 49); Cobb (92.5% good, AQI 36).
Air Quality Summary
Good Days
64.5%
176 of 273 monitored days
-10.5pp vs 75% target
Max AQI Recorded
84
Moderate
Health Grade
Moderate
90th-pct AQI 61
Gwinnett County, Good days share 64.5%
National avg
Share of monitored days at AQI 0-50 (Good band).
Gwinnett 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 273 monitored days across EPA AQI categories.
Good
176
64%
Moderate
97
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 Gwinnett County.
- PM2.5 · 154 days · 56.4%
- Ozone · 119 days · 43.6%
Health Impact Assessment
Moderate
Gwinnett County's air quality is rated Moderate based on 64.5% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 64.5% 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 PM2.5, driving AQI on 154 of 273 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Gwinnett County. Best year: 2020 (246 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 246 | 117 | 1 | 0 | 43 | 101 |
| 2021 | 173 | 149 | 2 | 0 | 49 | 108 |
| 2022 | 226 | 139 | 0 | 0 | 44 | 97 |
| 2023 | 186 | 172 | 7 | 0 | 50 | 140 |
| 2024 | 159 | 206 | 0 | 1 | 53 | 161 |
| 2025 | 176 | 97 | 0 | 0 | 45 | 84 |
How does Gwinnett County compare?
How Gwinnett County compares
Good-day share worse than US avg
Gwinnett County 64.5%
Bibb County, Georgia 49.5%
US average 76.5%
Median AQI worse than US avg
Gwinnett County 45
Bibb County, Georgia 51
US average 38
Unhealthy days / yr about average
Gwinnett County 0
Bibb County, Georgia 0
US average 0
Other Counties in Georgia
Air quality comparison for nearby counties in Georgia.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Gwinnett 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 Gwinnett County's air means for you
The air here stays in the breathable range year-round, with PM2.5 the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-PM2.5 days, the guide explains what a median of 45 means for exposure. Health guidance
- See how Gwinnett County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Gwinnett County with its Georgia neighbours before drawing a conclusion about the region. All of Georgia
Based on 273 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 Gwinnett County, Georgia? ▼
Gwinnett County has a median Air Quality Index (AQI) of 45, rated "Good." 64.5% of monitored days (176 out of 273) had good air quality in 2025.
What is the main pollutant in Gwinnett County? ▼
The primary pollutant in Gwinnett County is Fine Particles (PM2.5), which was the main AQI driver on 154 days (56% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Gwinnett County have? ▼
In 2025, Gwinnett County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 84.
Is the air quality in Gwinnett County getting better or worse? ▼
Air quality in Gwinnett County is worsening based on 5-year trends (2020-2025). Best year: 2020 with 246 good days. Worst year: 2024 with 159 good days.
What does AQI 45 mean for health? ▼
Gwinnett 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 Gwinnett County compare to other counties in Georgia? ▼
Gwinnett County has 64.5% good air days. Nearby counties in Georgia: Bibb (49.5% good), Charlton (79.0% good), Chatham (66.7% good), Clarke (66.7% good), Clayton (53.1% good), Cobb (92.5% good).
What is the 90th percentile AQI in Gwinnett County? ▼
The 90th percentile AQI for Gwinnett County is 61, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 84 (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.