Median AQI
31
Good
Idaho · County air quality · 2025
Bannock County, Idaho
Median AQI 31 (Good). 91.5% of monitored days rated Good, direct from EPA Air Quality System stations.
- 31
- Median AQI
- 91.5%
- Good-air days
- 0
- Unhealthy days
- 79%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Bannock County's air is good on balance, cleaner than most US counties, a median AQI of 31 with 91.5% of 304 monitored days in the Good band, driven mainly by PM10.
- 31
- median AQI · Good
- 91.5%
- days rated Good
- PM10
- main pollutant
- 79%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 111.
Data updated July 2026
- Good · 278 d · 91.4%
- Moderate · 25 d · 8.2%
- USG · 1 d · 0.3%
How did Bannock County's air break down in 2025?
Across 304 monitored days, 278 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 111 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 304 days monitored. Median AQI: 31 (Good).
Insights: Bannock County, Idaho. EPA monitors recorded a median Air Quality Index of 31 across 304 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 278 (91%) fell in the Good band (AQI 0–50), 25 (8%) registered Moderate readings, and 1 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 47, while the worst single-day peak hit 111 (USG). Residents averaged about 27.4 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM10 (163 days), Ozone (84 days), PM2.5 (57 days). Across the 2020–2025 trend window, good days shifted by -6 and the median AQI moved -7 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 111, usg but never Unhealthy. Nearby counties show comparable readings: Ada (80.6% good, AQI 39); Benewah (74.6% good, AQI 37); Blaine (99.4% good, AQI 22); Boise (72.9% good, AQI 43); Bonner (71.3% good, AQI 41); Bonneville (94.9% good, AQI 19).
Air Quality Summary
Good Days
91.5%
278 of 304 monitored days
16.5pp vs 75% target
Max AQI Recorded
111
USG
Health Grade
Excellent
90th-pct AQI 47
Bannock County, Good days share 91.5%
National avg
Share of monitored days at AQI 0-50 (Good band).
Bannock 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
278
91%
Moderate
25
8%
USG
1
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 Bannock County.
- PM10 · 163 days · 53.6%
- Ozone · 84 days · 27.6%
- PM2.5 · 57 days · 18.8%
Health Impact Assessment
Excellent
Bannock County's air quality is rated Excellent based on 91.5% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 91.5% of monitored days in 2025, with a median AQI of 31. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM10, driving AQI on 163 of 304 monitored days.
5-Year Air Quality Trend
Air quality is improving in Bannock County. Best year: 2023 (293 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 284 | 72 | 2 | 4 | 38 | 165 |
| 2021 | 245 | 112 | 7 | 1 | 44 | 155 |
| 2022 | 270 | 93 | 2 | 0 | 40 | 140 |
| 2023 | 293 | 39 | 2 | 0 | 41 | 557 |
| 2024 | 286 | 78 | 2 | 0 | 39 | 104 |
| 2025 | 278 | 25 | 1 | 0 | 31 | 111 |
How does Bannock County compare?
How Bannock County compares
Good-day share better than US avg
Bannock County 91.5%
Ada County, Idaho 80.6%
US average 76.5%
Median AQI better than US avg
Bannock County 31
Ada County, Idaho 39
US average 38
Unhealthy days / yr about average
Bannock 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 Bannock County.
Clark County, Washington
AQI 31 · 89.3% good
Erie County, Pennsylvania
AQI 31 · 81.4% good
Honolulu County, Hawaii
AQI 31 · 95.0% good
Josephine County, Oregon
AQI 31 · 76.2% good
Monroe County, Wisconsin
AQI 31 · 75.2% good
Montgomery County, Tennessee
AQI 31 · 84.7% good
What Bannock County's air means for you
The air here stays in the breathable range year-round, with PM10 the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-PM10 days, the guide explains what a median of 31 means for exposure. Health guidance
- See how Bannock County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Bannock County with its Idaho neighbours before drawing a conclusion about the region. All of Idaho
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 Bannock County, Idaho? ▼
Bannock County has a median Air Quality Index (AQI) of 31, rated "Good." 91.5% of monitored days (278 out of 304) had good air quality in 2025.
What is the main pollutant in Bannock County? ▼
The primary pollutant in Bannock County is Coarse Particles (PM10), which was the main AQI driver on 163 days (54% of monitored days). Irritates airways and can aggravate asthma and bronchitis.
How many unhealthy air days does Bannock County have? ▼
In 2025, Bannock County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 111.
Is the air quality in Bannock County getting better or worse? ▼
Air quality in Bannock County is improving based on 5-year trends (2020-2025). Best year: 2023 with 293 good days. Worst year: 2021 with 245 good days.
What does AQI 31 mean for health? ▼
Bannock County's median AQI of 31 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 Bannock County compare to other counties in Idaho? ▼
Bannock County has 91.5% good air days. Nearby counties in Idaho: Ada (80.6% good), Benewah (74.6% good), Blaine (99.4% good), Boise (72.9% good), Bonner (71.3% good), Bonneville (94.9% good).
What is the 90th percentile AQI in Bannock County? ▼
The 90th percentile AQI for Bannock County is 47, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 111 (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.