Median AQI
33
Good
Texas · County air quality · 2025
Brazoria County, Texas
Median AQI 33 (Good). 84.8% of monitored days rated Good, direct from EPA Air Quality System stations.
- 33
- Median AQI
- 84.8%
- Good-air days
- 0
- Unhealthy days
- 65%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Brazoria County's air is good on balance, cleaner than the median US county, a median AQI of 33 with 84.8% of 243 monitored days in the Good band, driven mainly by Ozone.
- 33
- median AQI · Good
- 84.8%
- days rated Good
- Ozone
- main pollutant
- 65%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 122.
Data updated July 2026
- Good · 206 d · 84.8%
- Moderate · 35 d · 14.4%
- USG · 2 d · 0.8%
How did Brazoria County's air break down in 2025?
Across 243 monitored days, 206 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 122 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 243 days monitored. Median AQI: 33 (Good).
Insights: Brazoria County, Texas. EPA monitors recorded a median Air Quality Index of 33 across 243 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 206 (85%) fell in the Good band (AQI 0–50), 35 (14%) registered Moderate readings, and 2 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 61, while the worst single-day peak hit 122 (USG). Residents averaged about 25.4 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (219 days), PM2.5 (18 days), NO2 (6 days). Across the 2020–2025 trend window, good days shifted by -122 and the median AQI moved +0 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 122, usg but never Unhealthy. Nearby counties show comparable readings: Atascosa (58.0% good, AQI 45); Bell (61.3% good, AQI 47); Bexar (39.8% good, AQI 53); Bowie (57.3% good, AQI 47); Brazos (63.4% good, AQI 43); Brewster (69.0% good, AQI 44).
Air Quality Summary
Good Days
84.8%
206 of 243 monitored days
9.8pp vs 75% target
Max AQI Recorded
122
USG
Health Grade
Good
90th-pct AQI 61
Brazoria County, Good days share 84.8%
National avg
Share of monitored days at AQI 0-50 (Good band).
Brazoria 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 243 monitored days across EPA AQI categories.
Good
206
85%
Moderate
35
14%
USG
2
1%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Brazoria County.
- Ozone · 219 days · 90.1%
- PM2.5 · 18 days · 7.4%
- NO₂ · 6 days · 2.5%
Health Impact Assessment
Good
Brazoria County's air quality is rated Good based on 84.8% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 84.8% of monitored days in 2025, with a median AQI of 33. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 219 of 243 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Brazoria County. Best year: 2021 (331 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 328 | 34 | 2 | 1 | 33 | 182 |
| 2021 | 331 | 22 | 11 | 1 | 34 | 159 |
| 2022 | 311 | 46 | 8 | 0 | 35 | 119 |
| 2023 | 301 | 47 | 16 | 1 | 36 | 156 |
| 2024 | 303 | 56 | 5 | 1 | 37 | 164 |
| 2025 | 206 | 35 | 2 | 0 | 33 | 122 |
How does Brazoria County compare?
How Brazoria County compares
Good-day share better than US avg
Brazoria County 84.8%
Atascosa County, Texas 58.0%
US average 76.5%
Median AQI better than US avg
Brazoria County 33
Atascosa County, Texas 45
US average 38
Unhealthy days / yr about average
Brazoria County 0
Atascosa County, Texas 0
US average 0
Other Counties in Texas
Air quality comparison for nearby counties in Texas.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Brazoria County.
Ascension County, Louisiana
AQI 33 · 94.1% good
Athens County, Ohio
AQI 33 · 80.3% good
Bristol City County, Virginia
AQI 33 · 78.3% good
Carter County, Oklahoma
AQI 33 · 80.9% good
Codington County, South Dakota
AQI 33 · 82.1% good
Del Norte County, California
AQI 33 · 81.0% good
What Brazoria 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 33 means for exposure. Health guidance
- See how Brazoria County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Brazoria County with its Texas neighbours before drawing a conclusion about the region. All of Texas
Based on 243 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 Brazoria County, Texas? ▼
Brazoria County has a median Air Quality Index (AQI) of 33, rated "Good." 84.8% of monitored days (206 out of 243) had good air quality in 2025.
What is the main pollutant in Brazoria County? ▼
The primary pollutant in Brazoria County is Ozone (O3), which was the main AQI driver on 219 days (90% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Brazoria County have? ▼
In 2025, Brazoria County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 122.
Is the air quality in Brazoria County getting better or worse? ▼
Air quality in Brazoria County is worsening based on 5-year trends (2020-2025). Best year: 2021 with 331 good days. Worst year: 2025 with 206 good days.
What does AQI 33 mean for health? ▼
Brazoria County's median AQI of 33 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 Brazoria County compare to other counties in Texas? ▼
Brazoria County has 84.8% good air days. Nearby counties in Texas: Atascosa (58.0% good), Bell (61.3% good), Bexar (39.8% good), Bowie (57.3% good), Brazos (63.4% good), Brewster (69.0% good).
What is the 90th percentile AQI in Brazoria County? ▼
The 90th percentile AQI for Brazoria County is 61, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 122 (USG).
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.