Median AQI
22
Good
Idaho · County air quality · 2025
Blaine County, Idaho
Median AQI 22 (Good). 99.4% of monitored days rated Good, direct from EPA Air Quality System stations.
- 22
- Median AQI
- 99.4%
- Good-air days
- 0
- Unhealthy days
- 95%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Blaine County's air is good on balance, among the cleanest 5% of US counties, a median AQI of 22 with 99.4% of 166 monitored days in the Good band, driven mainly by PM2.5.
- 22
- median AQI · Good
- 99.4%
- days rated Good
- PM2.5
- main pollutant
- 95%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 56.
Data updated July 2026
- Good · 165 d · 99.4%
- Moderate · 1 d · 0.6%
How did Blaine County's air break down in 2025?
Across 166 monitored days, 165 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 56 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 166 days monitored. Median AQI: 22 (Good).
Insights: Blaine County, Idaho. EPA monitors recorded a median Air Quality Index of 22 across 166 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 165 (99%) fell in the Good band (AQI 0–50), 1 (1%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 33, while the worst single-day peak hit 56 (Moderate). Residents averaged about 29.8 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (166 days). Across the 2020–2025 trend window, good days shifted by -158 and the median AQI moved +3 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 56, 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); Boise (72.9% good, AQI 43); Bonner (71.3% good, AQI 41); Bonneville (94.9% good, AQI 19).
Air Quality Summary
Good Days
99.4%
165 of 166 monitored days
24.4pp vs 75% target
Max AQI Recorded
56
Moderate
Health Grade
Excellent
90th-pct AQI 33
Blaine County, Good days share 99.4%
National avg
Share of monitored days at AQI 0-50 (Good band).
Blaine 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 166 monitored days across EPA AQI categories.
Good
165
99%
Moderate
1
1%
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 Blaine County.
- PM2.5 · 166 days · 100.0%
Health Impact Assessment
Excellent
Blaine County's air quality is rated Excellent based on 99.4% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 99.4% of monitored days in 2025, with a median AQI of 22. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 166 of 166 monitored days.
5-Year Air Quality Trend
Air quality is improving in Blaine County. Best year: 2023 (323 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 323 | 34 | 6 | 2 | 19 | 172 |
| 2021 | 288 | 52 | 10 | 0 | 23 | 144 |
| 2022 | 321 | 29 | 2 | 3 | 23 | 182 |
| 2023 | 323 | 7 | 0 | 0 | 19 | 63 |
| 2024 | 310 | 43 | 4 | 1 | 19 | 220 |
| 2025 | 165 | 1 | 0 | 0 | 22 | 56 |
How does Blaine County compare?
How Blaine County compares
Good-day share better than US avg
Blaine County 99.4%
Ada County, Idaho 80.6%
US average 76.5%
Median AQI better than US avg
Blaine County 22
Ada County, Idaho 39
US average 38
Unhealthy days / yr about average
Blaine 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 Blaine County.
Cass County, Minnesota
AQI 22 · 94.4% good
Chase County, Kansas
AQI 22 · 88.9% good
Deschutes County, Oregon
AQI 22 · 93.4% good
Douglas County, Nevada
AQI 22 · 90.9% good
Franklin County, Idaho
AQI 22 · 95.8% good
Franklin County, Washington
AQI 22 · 93.7% good
What Blaine 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 22 means for exposure. Health guidance
- See how Blaine County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Blaine County with its Idaho neighbours before drawing a conclusion about the region. All of Idaho
Based on 166 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 Blaine County, Idaho? ▼
Blaine County has a median Air Quality Index (AQI) of 22, rated "Good." 99.4% of monitored days (165 out of 166) had good air quality in 2025.
What is the main pollutant in Blaine County? ▼
The primary pollutant in Blaine County is Fine Particles (PM2.5), which was the main AQI driver on 166 days (100% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Blaine County have? ▼
In 2025, Blaine County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 56.
Is the air quality in Blaine County getting better or worse? ▼
Air quality in Blaine County is improving based on 5-year trends (2020-2025). Best year: 2023 with 323 good days. Worst year: 2025 with 165 good days.
What does AQI 22 mean for health? ▼
Blaine County's median AQI of 22 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 Blaine County compare to other counties in Idaho? ▼
Blaine County has 99.4% good air days. Nearby counties in Idaho: Ada (80.6% good), Bannock (91.5% good), Benewah (74.6% good), Boise (72.9% good), Bonner (71.3% good), Bonneville (94.9% good).
What is the 90th percentile AQI in Blaine County? ▼
The 90th percentile AQI for Blaine County is 33, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 56 (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.