Median AQI
32
Good
Idaho · County air quality · 2025
Valley County, Idaho
Median AQI 32 (Good). 78.1% of monitored days rated Good, direct from EPA Air Quality System stations.
- 32
- Median AQI
- 78.1%
- Good-air days
- 0
- Unhealthy days
- 47%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Valley County's air is good on balance, more polluted than the median US county, a median AQI of 32 with 78.1% of 169 monitored days in the Good band, driven mainly by PM2.5.
- 32
- median AQI · Good
- 78.1%
- days rated Good
- PM2.5
- main pollutant
- 47%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 94.
Data updated July 2026
- Good · 132 d · 78.1%
- Moderate · 37 d · 21.9%
How did Valley County's air break down in 2025?
Across 169 monitored days, 132 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 94 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 169 days monitored. Median AQI: 32 (Good).
Insights: Valley County, Idaho. EPA monitors recorded a median Air Quality Index of 32 across 169 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 132 (78%) fell in the Good band (AQI 0–50), 37 (22%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 59, while the worst single-day peak hit 94 (Moderate). Residents averaged about 23.4 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (169 days). Across the 2020–2025 trend window, good days shifted by -73 and the median AQI moved -8 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 94, moderate but never Unhealthy. Nearby counties show comparable readings: Ada (80.6% good, AQI 39); Bannock (91.5% good, AQI 31); Benewah (74.6% good, AQI 37); Blaine (99.4% good, AQI 22); Boise (72.9% good, AQI 43); Bonner (71.3% good, AQI 41).
Air Quality Summary
Good Days
78.1%
132 of 169 monitored days
3.1pp vs 75% target
Max AQI Recorded
94
Moderate
Health Grade
Good
90th-pct AQI 59
Valley County, Good days share 78.1%
National avg
Share of monitored days at AQI 0-50 (Good band).
Valley 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 169 monitored days across EPA AQI categories.
Good
132
78%
Moderate
37
22%
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 Valley County.
- PM2.5 · 169 days · 100.0%
Health Impact Assessment
Good
Valley County's air quality is rated Good based on 78.1% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 78.1% of monitored days in 2025, with a median AQI of 32. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 169 of 169 monitored days.
5-Year Air Quality Trend
Air quality is improving in Valley County. Best year: 2023 (255 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 205 | 117 | 5 | 1 | 40 | 211 |
| 2021 | 217 | 125 | 7 | 2 | 41 | 162 |
| 2022 | 241 | 102 | 6 | 2 | 37 | 168 |
| 2023 | 255 | 105 | 0 | 0 | 36 | 78 |
| 2024 | 235 | 113 | 8 | 1 | 37 | 155 |
| 2025 | 132 | 37 | 0 | 0 | 32 | 94 |
How does Valley County compare?
How Valley County compares
Good-day share better than US avg
Valley County 78.1%
Ada County, Idaho 80.6%
US average 76.5%
Median AQI better than US avg
Valley County 32
Ada County, Idaho 39
US average 38
Unhealthy days / yr about average
Valley County 0
Ada County, Idaho 0
US average 0
Other Counties in Idaho
Air quality comparison for nearby counties in Idaho.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Valley County.
Archuleta County, Colorado
AQI 32 · 79.5% good
Clay County, Alabama
AQI 32 · 85.4% good
Elmore County, Alabama
AQI 32 · 97.2% good
Harrison County, West Virginia
AQI 32 · 73.3% good
Klamath County, Oregon
AQI 32 · 71.3% good
Liberty County, Florida
AQI 32 · 97.7% good
What Valley 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 32 means for exposure. Health guidance
- See how Valley County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Valley County with its Idaho neighbours before drawing a conclusion about the region. All of Idaho
Based on 169 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 Valley County, Idaho? ▼
Valley County has a median Air Quality Index (AQI) of 32, rated "Good." 78.1% of monitored days (132 out of 169) had good air quality in 2025.
What is the main pollutant in Valley County? ▼
The primary pollutant in Valley County is Fine Particles (PM2.5), which was the main AQI driver on 169 days (100% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Valley County have? ▼
In 2025, Valley County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 94.
Is the air quality in Valley County getting better or worse? ▼
Air quality in Valley County is improving based on 5-year trends (2020-2025). Best year: 2023 with 255 good days. Worst year: 2025 with 132 good days.
What does AQI 32 mean for health? ▼
Valley County's median AQI of 32 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 Valley County compare to other counties in Idaho? ▼
Valley County has 78.1% good air days. Nearby counties in Idaho: Ada (80.6% good), Bannock (91.5% good), Benewah (74.6% good), Blaine (99.4% good), Boise (72.9% good), Bonner (71.3% good).
What is the 90th percentile AQI in Valley County? ▼
The 90th percentile AQI for Valley County is 59, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 94 (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.