Median AQI
47
Good
Utah · County air quality · 2025
Carbon County, Utah
Median AQI 47 (Good). 62.9% of monitored days rated Good, direct from EPA Air Quality System stations.
- 47
- Median AQI
- 62.9%
- Good-air days
- 0
- Unhealthy days
- 19%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Carbon County's air is good on balance, among the more polluted 10% of US counties, a median AQI of 47 with 62.9% of 272 monitored days in the Good band, driven mainly by Ozone.
- 47
- median AQI · Good
- 62.9%
- days rated Good
- Ozone
- main pollutant
- 19%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 108.
Data updated July 2026
- Good · 171 d · 62.9%
- Moderate · 99 d · 36.4%
- USG · 2 d · 0.7%
How did Carbon County's air break down in 2025?
Across 272 monitored days, 171 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 108 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 272 days monitored. Median AQI: 47 (Good).
Insights: Carbon County, Utah. EPA monitors recorded a median Air Quality Index of 47 across 272 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 171 (63%) fell in the Good band (AQI 0–50), 99 (36%) registered Moderate readings, and 2 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 71, while the worst single-day peak hit 108 (USG). Residents averaged about 18.9 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (256 days), PM2.5 (16 days). Across the 2020–2025 trend window, good days shifted by -137 and the median AQI moved +4 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 108, usg but never Unhealthy. Nearby counties show comparable readings: Box Elder (60.0% good, AQI 48); Cache (61.2% good, AQI 46); Davis (59.5% good, AQI 48); Duchesne (59.4% good, AQI 47); Garfield (100.0% good, AQI 4); Grand (61.7% good, AQI 47).
Air Quality Summary
Good Days
62.9%
171 of 272 monitored days
-12.1pp vs 75% target
Max AQI Recorded
108
USG
Health Grade
Moderate
90th-pct AQI 71
Carbon County, Good days share 62.9%
National avg
Share of monitored days at AQI 0-50 (Good band).
Carbon 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 272 monitored days across EPA AQI categories.
Good
171
63%
Moderate
99
36%
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 Carbon County.
- Ozone · 256 days · 94.1%
- PM2.5 · 16 days · 5.9%
Health Impact Assessment
Moderate
Carbon County's air quality is rated Moderate based on 62.9% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 62.9% of monitored days in 2025, with a median AQI of 47. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 256 of 272 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Carbon County. Best year: 2023 (329 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 308 | 42 | 0 | 0 | 43 | 93 |
| 2021 | 265 | 88 | 10 | 2 | 44 | 155 |
| 2022 | 321 | 43 | 0 | 0 | 43 | 74 |
| 2023 | 329 | 34 | 0 | 0 | 42 | 70 |
| 2024 | 278 | 87 | 1 | 0 | 44 | 112 |
| 2025 | 171 | 99 | 2 | 0 | 47 | 108 |
How does Carbon County compare?
How Carbon County compares
Good-day share worse than US avg
Carbon County 62.9%
Box Elder County, Utah 60.0%
US average 76.5%
Median AQI worse than US avg
Carbon County 47
Box Elder County, Utah 48
US average 38
Unhealthy days / yr about average
Carbon County 0
Box Elder County, Utah 0
US average 0
Other Counties in Utah
Air quality comparison for nearby counties in Utah.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Carbon County.
Beaver County, Pennsylvania
AQI 47 · 54.3% good
Bell County, Texas
AQI 47 · 61.3% good
Bowie County, Texas
AQI 47 · 57.3% good
Bronx County, New York
AQI 47 · 56.6% good
Butte County, California
AQI 47 · 66.1% good
Calcasieu County, Louisiana
AQI 47 · 61.5% good
What Carbon 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 47 means for exposure. Health guidance
- See how Carbon County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Carbon County with its Utah neighbours before drawing a conclusion about the region. All of Utah
Based on 272 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 Carbon County, Utah? ▼
Carbon County has a median Air Quality Index (AQI) of 47, rated "Good." 62.9% of monitored days (171 out of 272) had good air quality in 2025.
What is the main pollutant in Carbon County? ▼
The primary pollutant in Carbon County is Ozone (O3), which was the main AQI driver on 256 days (94% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Carbon County have? ▼
In 2025, Carbon County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 108.
Is the air quality in Carbon County getting better or worse? ▼
Air quality in Carbon County is worsening based on 5-year trends (2020-2025). Best year: 2023 with 329 good days. Worst year: 2025 with 171 good days.
What does AQI 47 mean for health? ▼
Carbon County's median AQI of 47 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 Carbon County compare to other counties in Utah? ▼
Carbon County has 62.9% good air days. Nearby counties in Utah: Box Elder (60.0% good), Cache (61.2% good), Davis (59.5% good), Duchesne (59.4% good), Garfield (100.0% good), Grand (61.7% good).
What is the 90th percentile AQI in Carbon County? ▼
The 90th percentile AQI for Carbon County is 71, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 108 (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.