Median AQI
34
Good
Idaho · County air quality · 2025
Valley County, Idaho
Median AQI 34 (Good). 73.3% of monitored days rated Good, direct from EPA Air Quality System stations.
- 34
- Median AQI
- 73.3%
- Good-air days
- 0
- Unhealthy days
- 40%
- Cleaner than US counties
Valley County's 2025 annual median AQI is 34 (Good), with 73.3% Good days
According to the U.S. EPA Air Quality System, Valley County, Idaho posted a 2025 median AQI of 34 (Good) across 352 monitored days, with 73.3% 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
- Valley County's 73.3% Good-day share places it cleaner than 40% of US counties in 2025.
- Closest median-AQI peer
- Androscoggin County (85.2% Good, median AQI 34) is the closest nationwide median-AQI peer to Valley County.
- 2020–2025 trend
- Valley County's floor-qualifying Good-day share is improving from 2020 to 2025 (62.5% → 73.3%).
- Median AQI
- Median AQI: 34
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 34 with 73.3% of 352 monitored days in the Good band, driven mainly by PM2.5.
- 34
- median AQI · Good
- 73.3%
- days rated Good
- PM2.5
- main pollutant
- 40%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 104.
Annual release change
What changed in the 2025 EPA annual release
- Valley County's Good-day share rose from 65.8% to 73.3% between the 2024 and 2025 EPA annual releases, a change of +7.5 percentage points.
- Valley County's peak single-day AQI fell from 155 to 104 between the 2024 and 2025 EPA annual releases, a change of -51 points.
- Valley County's median AQI fell from 37 to 34 between the 2024 and 2025 EPA annual releases, a change of -3 points.
- Valley County's Unhealthy-category days fell from 1 to 0 between the 2024 and 2025 EPA annual releases, a change of -1 days.
Data updated August 2026
- Good · 258 d · 73.3%
- Moderate · 93 d · 26.4%
- USG · 1 d · 0.3%
How did Valley County's air break down in 2025?
Across 352 monitored days, 258 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 104 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 352 days monitored. Median AQI: 34 (Good).
Insights: Valley County, Idaho. EPA monitors recorded a median Air Quality Index of 34 across 352 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 258 (73%) fell in the Good band (AQI 0–50), 93 (26%) registered Moderate readings, and 1 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 60, while the worst single-day peak hit 104 (USG). Residents averaged about 22.0 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 +11.0 points (measured against 329 monitored days in 2020 and 352 in 2025, so raw day counts are not comparable) and the median AQI moved -6 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 104, 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
73.3%
258 of 352 monitored days
-1.7pp vs 75% target
Max AQI Recorded
104
USG
Health Grade
Moderate
90th-pct AQI 60
Valley County, Good days share 73.3%
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 352 monitored days across EPA AQI categories.
Good
258
73%
Moderate
93
26%
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 Valley County.
- PM2.5 · 352 days · 100.0%
Health Impact Assessment
Moderate
Valley County's air quality is rated Moderate based on 73.3% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 73.3% of monitored days in 2025, with a median AQI of 34. 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 improving in Valley County. Highest Good-day share: 2025 (73.3%, 258 of 352 monitored 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 | 258 | 93 | 1 | 0 | 34 | 104 |
How does Valley County compare?
How Valley County compares
Good-day share worse than US avg
Valley County 73.3%
Androscoggin County, Maine 85.2%
US average 76.0%
Median AQI better than US avg
Valley County 34
Androscoggin County, Maine 34
US average 39
Unhealthy days / yr better than US avg
Valley County 0
Androscoggin County, Maine 0
US average 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Valley County (34), not geographic neighbors.
Androscoggin County, Maine
Median AQI 34 · 85.2% Good-day share
Archuleta County, Colorado
Median AQI 34 · 83.0% Good-day share
Bristol City County, Virginia
Median AQI 34 · 78.0% Good-day share
Brown County, Indiana
Median AQI 34 · 95.9% Good-day share
Clark County, Arkansas
Median AQI 34 · 96.7% Good-day share
Clay County, South Dakota
Median AQI 34 · 87.8% 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).
Broward County, Florida
73.4% Good-day share · median AQI 43
Buncombe County, North Carolina
73.4% Good-day share · median AQI 40
Jefferson County, Missouri
73.4% Good-day share · median AQI 42
Providence County, Rhode Island
73.4% Good-day share · median AQI 39
Brown County, Wisconsin
73.2% Good-day share · median AQI 37
Dakota County, Minnesota
73.2% Good-day share · median AQI 35
Idaho counties on the map
Geographic containment only, other monitored counties in Idaho, independent of AQI or pollutant match.
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 34 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 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 Valley County, Idaho? ▼
Valley County has a median Air Quality Index (AQI) of 34, rated "Good." 73.3% of monitored days (258 out of 352) 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 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 Valley County have? ▼
In 2025, Valley County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 104.
Is the air quality in Valley County getting better or worse? ▼
Air quality in Valley County is improving across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2025 at 73.3% (258 of 352 days). Lowest qualifying Good-day share: 2021 at 61.8% (217 of 351 days).
What does AQI 34 mean for health? ▼
Valley County's median AQI of 34 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Valley County compare to other counties in Idaho? ▼
Valley County has 73.3% 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 Valley County? ▼
The 90th percentile AQI for Valley County is 60, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 104 (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 Valley County, Idaho · 2020–2025
Share this annual record
Send the source-year summary or download its ready-to-use data card.
Download this county's annual AQI row as CSV , with the same EPA fields and denominator shown on this page.
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.