Median AQI
31
Good
Idaho · County air quality · 2025
Kootenai County, Idaho
Median AQI 31 (Good). 77.8% of monitored days rated Good, direct from EPA Air Quality System stations.
- 31
- Median AQI
- 77.8%
- Good-air days
- 0
- Unhealthy days
- 51%
- Cleaner than US counties
Kootenai County's 2025 annual median AQI is 31 (Good), with 77.8% Good days
According to the U.S. EPA Air Quality System, Kootenai County, Idaho posted a 2025 median AQI of 31 (Good) across 352 monitored days, with 77.8% rated Good and 0 unhealthy or worse. This is an annual comparison, not today's advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US
- Kootenai County's 77.8% Good-day share places it cleaner than 51% of US counties in 2025.
- Closest median-AQI peer
- Athens County (83.4% Good, median AQI 31) is the closest nationwide median-AQI peer to Kootenai County.
- 2020–2025 trend
- Kootenai County's floor-qualifying Good-day share is worsening from 2020 to 2025 (82.5% → 77.8%).
- Median AQI
- Median AQI: 31
The verdict
According to EPA Air Quality System monitoring data, Kootenai County's air is good on balance, cleaner than the median US county, a median AQI of 31 with 77.8% of 352 monitored days in the Good band, driven mainly by PM2.5.
- 31
- median AQI · Good
- 77.8%
- days rated Good
- PM2.5
- main pollutant
- 51%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 118.
Annual release change
What changed in the 2025 EPA annual release
- Kootenai County's Good-day share fell from 82.0% to 77.8% between the 2024 and 2025 EPA annual releases, a change of -4.1 percentage points.
- Kootenai County's median AQI rose from 24 to 31 between the 2024 and 2025 EPA annual releases, a change of +7 points.
Data updated August 2026
- Good · 274 d · 77.8%
- Moderate · 75 d · 21.3%
- USG · 3 d · 0.9%
How did Kootenai County's air break down in 2025?
Across 352 monitored days, 274 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 118 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 352 days monitored. Median AQI: 31 (Good).
Insights: Kootenai County, Idaho. EPA monitors recorded a median Air Quality Index of 31 across 352 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 274 (78%) fell in the Good band (AQI 0–50), 75 (21%) registered Moderate readings, and 3 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 58, while the worst single-day peak hit 118 (USG). Residents averaged about 23.4 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (352 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by -3.5 points and the median AQI moved +5 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 118, usg but never Unhealthy. Nearby counties show comparable readings: Ada (74.0% good, AQI 42); Bannock (88.8% good, AQI 36); Benewah (63.4% good, AQI 41); Blaine (96.6% good, AQI 17); Boise (70.4% good, AQI 42); Bonner (56.2% good, AQI 47).
Air Quality Summary
Good Days
77.8%
274 of 352 monitored days
2.8pp vs 75% target
Max AQI Recorded
118
USG
Health Grade
Good
90th-pct AQI 58
Kootenai County, Good days share 77.8%
National avg
Share of monitored days at AQI 0-50 (Good band).
Kootenai 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 352 monitored days across EPA AQI categories.
Good
274
78%
Moderate
75
21%
USG
3
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 Kootenai County.
- PM2.5 · 352 days · 100.0%
Health Impact Assessment
Good
Kootenai County's air quality is rated Good based on 77.8% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 77.8% 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 PM2.5, driving AQI on 352 of 352 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Kootenai County. Highest Good-day share: 2020 (82.5%, 288 of 354 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 288 | 58 | 1 | 2 | 26 | 518 |
| 2021 | 268 | 81 | 3 | 5 | 31 | 195 |
| 2022 | 264 | 88 | 4 | 3 | 29 | 186 |
| 2023 | 279 | 78 | 2 | 1 | 32 | 222 |
| 2024 | 291 | 63 | 1 | 0 | 24 | 109 |
| 2025 | 274 | 75 | 3 | 0 | 31 | 118 |
How does Kootenai County compare?
How Kootenai County compares
Good-day share better than typical
Kootenai County 77.8%
Athens County, Ohio 83.4%
Typical US county 76.0%
Median AQI better than typical
Kootenai County 31
Athens County, Ohio 31
Typical US county 39
Unhealthy days / yr better than typical
Kootenai County 0
Athens County, Ohio 0
Typical US county 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Kootenai County (31), not geographic neighbors.
Athens County, Ohio
Median AQI 31 · 83.4% Good-day share
Clackamas County, Oregon
Median AQI 31 · 87.6% Good-day share
Grant County, Oklahoma
Median AQI 31 · 82.3% Good-day share
Kent County, Rhode Island
Median AQI 31 · 92.8% Good-day share
Lake County, California
Median AQI 31 · 99.2% Good-day share
Lake County, Minnesota
Median AQI 31 · 85.9% Good-day share
Same primary pollutant: PM2.5
PM2.5 led the AQI on the most monitored days here. These peers share that driver and the closest Good-day share (a second relationship type beyond median-AQI neighbors).
Crow Wing County, Minnesota
77.8% Good-day share · median AQI 37
Warren County, Kentucky
77.8% Good-day share · median AQI 39
Codington County, South Dakota
78.0% Good-day share · median AQI 35
Bristol City County, Virginia
78.0% Good-day share · median AQI 34
Sumter County, Alabama
78.0% Good-day share · median AQI 41
Cass County, Missouri
77.6% Good-day share · median AQI 41
Idaho counties on the map
Geographic containment only, other monitored counties in Idaho, independent of AQI or pollutant match.
What Kootenai 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 31 means for exposure. Health guidance
- See how Kootenai County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Kootenai County with its Idaho neighbours before drawing a conclusion about the region. All of Idaho
Based on 352 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
Keep exploring the annual AQI record
Air-quality reading list
Frequently Asked Questions
What is the air quality in Kootenai County, Idaho? ▼
Kootenai County has a median Air Quality Index (AQI) of 31, rated "Good." 77.8% of monitored days (274 out of 352) had good air quality in 2025.
What is the main pollutant in Kootenai County? ▼
The primary pollutant in Kootenai County is Fine Particles (PM2.5), which was the main AQI driver on 352 days (100% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Kootenai County have? ▼
In 2025, Kootenai County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 118.
Is the air quality in Kootenai County getting better or worse? ▼
Air quality in Kootenai County is worsening across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2020 at 82.5% (288 of 354 days). Lowest qualifying Good-day share: 2022 at 73.5% (264 of 359 days).
What does AQI 31 mean for health? ▼
Kootenai County's median AQI of 31 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Kootenai County compare to other counties in Idaho? ▼
Kootenai County has 77.8% good air days. Nearby counties in Idaho: Ada (74.0% good), Bannock (88.8% good), Benewah (63.4% good), Blaine (96.6% good), Boise (70.4% good), Bonner (56.2% good).
What is the 90th percentile AQI in Kootenai County? ▼
The 90th percentile AQI for Kootenai County is 58, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 118 (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. Spotted a figure that looks wrong? Report a correction.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for Kootenai County, Idaho · 2020–2025
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Every figure on PlainAirData 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.