Median AQI
30
Good
Idaho · County air quality · 2025
Canyon County, Idaho
Median AQI 30 (Good). 87.2% of monitored days rated Good, direct from EPA Air Quality System stations.
- 30
- Median AQI
- 87.2%
- Good-air days
- 0
- Unhealthy days
- 70%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Canyon County's air is good on balance, cleaner than the median US county, a median AQI of 30 with 87.2% of 179 monitored days in the Good band, driven mainly by PM2.5.
- 30
- median AQI · Good
- 87.2%
- days rated Good
- PM2.5
- main pollutant
- 70%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 65.
Data updated July 2026
- Good · 156 d · 87.2%
- Moderate · 23 d · 12.8%
How did Canyon County's air break down in 2025?
Across 179 monitored days, 156 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 65 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 179 days monitored. Median AQI: 30 (Good).
Insights: Canyon County, Idaho. EPA monitors recorded a median Air Quality Index of 30 across 179 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 156 (87%) fell in the Good band (AQI 0–50), 23 (13%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 53, while the worst single-day peak hit 65 (Moderate). Residents averaged about 26.1 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (164 days), PM10 (15 days). Across the 2020–2025 trend window, good days shifted by -54 and the median AQI moved -12 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 65, 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
87.2%
156 of 179 monitored days
12.2pp vs 75% target
Max AQI Recorded
65
Moderate
Health Grade
Good
90th-pct AQI 53
Canyon County, Good days share 87.2%
National avg
Share of monitored days at AQI 0-50 (Good band).
Canyon 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 179 monitored days across EPA AQI categories.
Good
156
87%
Moderate
23
13%
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 Canyon County.
- PM2.5 · 164 days · 91.6%
- PM10 · 15 days · 8.4%
Health Impact Assessment
Good
Canyon County's air quality is rated Good based on 87.2% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 87.2% of monitored days in 2025, with a median AQI of 30. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 164 of 179 monitored days.
5-Year Air Quality Trend
Air quality is improving in Canyon County. Best year: 2023 (268 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 210 | 140 | 10 | 6 | 42 | 158 |
| 2021 | 209 | 147 | 5 | 4 | 46 | 172 |
| 2022 | 189 | 167 | 7 | 1 | 49 | 155 |
| 2023 | 268 | 96 | 0 | 0 | 34 | 88 |
| 2024 | 248 | 103 | 9 | 6 | 36 | 183 |
| 2025 | 156 | 23 | 0 | 0 | 30 | 65 |
How does Canyon County compare?
How Canyon County compares
Good-day share better than US avg
Canyon County 87.2%
Ada County, Idaho 80.6%
US average 76.5%
Median AQI better than US avg
Canyon County 30
Ada County, Idaho 39
US average 38
Unhealthy days / yr about average
Canyon 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 Canyon County.
Guaynabo County, Puerto Rico
AQI 30 · 86.0% good
Hawaii County, Hawaii
AQI 30 · 81.1% good
Lynchburg City County, Virginia
AQI 30 · 84.2% good
Putnam County, Tennessee
AQI 30 · 88.6% good
Salem City County, Virginia
AQI 30 · 79.6% good
Whatcom County, Washington
AQI 30 · 96.6% good
What Canyon 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 30 means for exposure. Health guidance
- See how Canyon County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Canyon County with its Idaho neighbours before drawing a conclusion about the region. All of Idaho
Based on 179 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 Canyon County, Idaho? ▼
Canyon County has a median Air Quality Index (AQI) of 30, rated "Good." 87.2% of monitored days (156 out of 179) had good air quality in 2025.
What is the main pollutant in Canyon County? ▼
The primary pollutant in Canyon County is Fine Particles (PM2.5), which was the main AQI driver on 164 days (92% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Canyon County have? ▼
In 2025, Canyon County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 65.
Is the air quality in Canyon County getting better or worse? ▼
Air quality in Canyon County is improving based on 5-year trends (2020-2025). Best year: 2023 with 268 good days. Worst year: 2025 with 156 good days.
What does AQI 30 mean for health? ▼
Canyon County's median AQI of 30 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 Canyon County compare to other counties in Idaho? ▼
Canyon County has 87.2% 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 Canyon County? ▼
The 90th percentile AQI for Canyon County is 53, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 65 (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.