Median AQI
48
Good
Texas · County air quality · 2025
Galveston County, Texas
Median AQI 48 (Good). 54.3% of monitored days rated Good, direct from EPA Air Quality System stations.
- 48
- Median AQI
- 54.3%
- Good-air days
- 2
- Unhealthy days
- 10%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Galveston County's air is good on balance, among the more polluted 10% of US counties, a median AQI of 48 with 54.3% of 243 monitored days in the Good band, driven mainly by PM2.5.
- 48
- median AQI · Good
- 54.3%
- days rated Good
- PM2.5
- main pollutant
- 10%
- cleaner than US counties
2 days reached Unhealthy or worse; the worst single reading hit AQI 179.
Data updated July 2026
- Good · 132 d · 54.3%
- Moderate · 105 d · 43.2%
- USG · 4 d · 1.6%
- Unhealthy · 2 d · 0.8%
How did Galveston County's air break down in 2025?
Across 243 monitored days, 132 fell in the Good band (AQI 0–50) and 2 reached Unhealthy or worse. The worst single day peaked at AQI 179 (Unhealthy).
EPA AQS →Air quality data from EPA Air Quality System (2025). 243 days monitored. Median AQI: 48 (Good).
Insights: Galveston County, Texas. EPA monitors recorded a median Air Quality Index of 48 across 243 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 132 (54%) fell in the Good band (AQI 0–50), 105 (43%) registered Moderate readings, and 4 (2%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 67, while the worst single-day peak hit 179 (Unhealthy). Residents averaged about 16.3 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (126 days), Ozone (117 days). Across the 2020–2025 trend window, good days shifted by -106 and the median AQI moved +4 points, placing the multi-year trajectory at worsening. Residents and visitors experienced 2 unhealthy-or-worse days combined, periods when the EPA recommends sensitive groups limit prolonged outdoor exertion. 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); Brazoria (84.8% good, AQI 33); Brazos (63.4% good, AQI 43).
Air Quality Summary
Good Days
54.3%
132 of 243 monitored days
-20.7pp vs 75% target
Max AQI Recorded
179
Unhealthy
Health Grade
Moderate
90th-pct AQI 67
Galveston County, Good days share 54.3%
National avg
Share of monitored days at AQI 0-50 (Good band).
Galveston County, Unhealthy-or-worse share 0.8%
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
132
54%
Moderate
105
43%
USG
4
2%
Unhealthy
2
1%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Galveston County.
- PM2.5 · 126 days · 51.9%
- Ozone · 117 days · 48.1%
Health Impact Assessment
Moderate
Galveston County's air quality is rated Moderate based on 54.3% good air days. There were 2 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 4 days reached "Unhealthy for Sensitive Groups" (AQI 101-150) and peak AQI reached 179. Sensitive groups should monitor real-time conditions at AirNow.gov.
The dominant pollutant is PM2.5, driving AQI on 126 of 243 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Galveston County. Best year: 2021 (259 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 238 | 119 | 3 | 0 | 44 | 143 |
| 2021 | 259 | 99 | 3 | 0 | 43 | 122 |
| 2022 | 236 | 122 | 6 | 1 | 46 | 159 |
| 2023 | 177 | 164 | 19 | 2 | 51 | 159 |
| 2024 | 245 | 109 | 6 | 2 | 44 | 159 |
| 2025 | 132 | 105 | 4 | 2 | 48 | 179 |
How does Galveston County compare?
How Galveston County compares
Good-day share worse than US avg
Galveston County 54.3%
Atascosa County, Texas 58.0%
US average 76.5%
Median AQI worse than US avg
Galveston County 48
Atascosa County, Texas 45
US average 38
Unhealthy days / yr worse than US avg
Galveston County 2
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 Galveston County.
Black Hawk County, Iowa
AQI 48 · 56.6% good
Box Elder County, Utah
AQI 48 · 60.0% good
Brookings County, South Dakota
AQI 48 · 53.0% good
Clear Creek County, Colorado
AQI 48 · 64.4% good
Coconino County, Arizona
AQI 48 · 62.5% good
Columbia County, Florida
AQI 48 · 56.4% good
What Galveston County's air means for you
On most days the air here is fine, but PM2.5 drives 2 unhealthy-or-worse days a year that sensitive groups should plan around.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-PM2.5 days, the guide explains what a median of 48 means for exposure. Health guidance
- See how Galveston County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Galveston 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 Galveston County, Texas? ▼
Galveston County has a median Air Quality Index (AQI) of 48, rated "Good." 54.3% of monitored days (132 out of 243) had good air quality in 2025.
What is the main pollutant in Galveston County? ▼
The primary pollutant in Galveston County is Fine Particles (PM2.5), which was the main AQI driver on 126 days (52% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Galveston County have? ▼
In 2025, Galveston County recorded 2 unhealthy air days (2 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 179.
Is the air quality in Galveston County getting better or worse? ▼
Air quality in Galveston County is worsening based on 5-year trends (2020-2025). Best year: 2021 with 259 good days. Worst year: 2025 with 132 good days.
What does AQI 48 mean for health? ▼
Galveston County's median AQI of 48 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 Galveston County compare to other counties in Texas? ▼
Galveston County has 54.3% good air days. Nearby counties in Texas: Atascosa (58.0% good), Bell (61.3% good), Bexar (39.8% good), Bowie (57.3% good), Brazoria (84.8% good), Brazos (63.4% good).
What is the 90th percentile AQI in Galveston County? ▼
The 90th percentile AQI for Galveston County is 67, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 179 (Unhealthy).
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.