Median AQI
48
Good
Utah · County air quality · 2025
Davis County, Utah
Median AQI 48 (Good). 59.5% of monitored days rated Good, direct from EPA Air Quality System stations.
- 48
- Median AQI
- 59.5%
- Good-air days
- 0
- Unhealthy days
- 14%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Davis County's air is good on balance, among the more polluted 10% of US counties, a median AQI of 48 with 59.5% of 304 monitored days in the Good band, driven mainly by Ozone.
- 48
- median AQI · Good
- 59.5%
- days rated Good
- Ozone
- main pollutant
- 14%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 119.
Data updated July 2026
- Good · 181 d · 59.5%
- Moderate · 116 d · 38.2%
- USG · 7 d · 2.3%
How did Davis County's air break down in 2025?
Across 304 monitored days, 181 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 119 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 304 days monitored. Median AQI: 48 (Good).
Insights: Davis County, Utah. EPA monitors recorded a median Air Quality Index of 48 across 304 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 181 (60%) fell in the Good band (AQI 0–50), 116 (38%) registered Moderate readings, and 7 (2%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 80, while the worst single-day peak hit 119 (USG). Residents averaged about 17.9 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (246 days), PM2.5 (43 days), NO2 (11 days), PM10 (4 days). Across the 2020–2025 trend window, good days shifted by -36 and the median AQI moved +2 points, placing the multi-year trajectory at stable. The worst single reading over the 2020–2025 window was AQI 119, usg but never Unhealthy. Nearby counties show comparable readings: Box Elder (60.0% good, AQI 48); Cache (61.2% good, AQI 46); Carbon (62.9% good, AQI 47); Duchesne (59.4% good, AQI 47); Garfield (100.0% good, AQI 4); Grand (61.7% good, AQI 47).
Air Quality Summary
Good Days
59.5%
181 of 304 monitored days
-15.5pp vs 75% target
Max AQI Recorded
119
USG
Health Grade
Moderate
90th-pct AQI 80
Davis County, Good days share 59.5%
National avg
Share of monitored days at AQI 0-50 (Good band).
Davis 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 304 monitored days across EPA AQI categories.
Good
181
60%
Moderate
116
38%
USG
7
2%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Davis County.
- Ozone · 246 days · 80.9%
- PM2.5 · 43 days · 14.1%
- NO₂ · 11 days · 3.6%
- PM10 · 4 days · 1.3%
Health Impact Assessment
Moderate
Davis County's air quality is rated Moderate based on 59.5% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 59.5% of monitored days in 2025, with a median AQI of 48. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 246 of 304 monitored days.
5-Year Air Quality Trend
Air quality is stable in Davis County. Best year: 2024 (234 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 217 | 135 | 13 | 1 | 46 | 157 |
| 2021 | 205 | 134 | 25 | 1 | 47 | 156 |
| 2022 | 210 | 145 | 10 | 0 | 47 | 147 |
| 2023 | 211 | 141 | 12 | 1 | 47 | 151 |
| 2024 | 234 | 117 | 15 | 0 | 46 | 133 |
| 2025 | 181 | 116 | 7 | 0 | 48 | 119 |
How does Davis County compare?
How Davis County compares
Good-day share worse than US avg
Davis County 59.5%
Box Elder County, Utah 60.0%
US average 76.5%
Median AQI worse than US avg
Davis County 48
Box Elder County, Utah 48
US average 38
Unhealthy days / yr about average
Davis 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 Davis 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 Davis 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 48 means for exposure. Health guidance
- See how Davis County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Davis County with its Utah neighbours before drawing a conclusion about the region. All of Utah
Based on 304 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 Davis County, Utah? ▼
Davis County has a median Air Quality Index (AQI) of 48, rated "Good." 59.5% of monitored days (181 out of 304) had good air quality in 2025.
What is the main pollutant in Davis County? ▼
The primary pollutant in Davis County is Ozone (O3), which was the main AQI driver on 246 days (81% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Davis County have? ▼
In 2025, Davis County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 119.
Is the air quality in Davis County getting better or worse? ▼
Air quality in Davis County is stable based on 5-year trends (2020-2025). Best year: 2024 with 234 good days. Worst year: 2025 with 181 good days.
What does AQI 48 mean for health? ▼
Davis 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 Davis County compare to other counties in Utah? ▼
Davis County has 59.5% good air days. Nearby counties in Utah: Box Elder (60.0% good), Cache (61.2% good), Carbon (62.9% good), Duchesne (59.4% good), Garfield (100.0% good), Grand (61.7% good).
What is the 90th percentile AQI in Davis County? ▼
The 90th percentile AQI for Davis County is 80, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 119 (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.