Median AQI
12
Good
Montana · County air quality · 2025
Teton County, Montana
Median AQI 12 (Good). 97.1% of monitored days rated Good, direct from EPA Air Quality System stations.
- 12
- Median AQI
- 97.1%
- Good-air days
- 0
- Unhealthy days
- 96%
- Cleaner than US counties
Teton County's 2025 annual median AQI is 12 (Good), with 97.1% Good days
According to the U.S. EPA Air Quality System, Teton County, Montana posted a 2025 median AQI of 12 (Good) across 277 monitored days, with 97.1% 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
- Teton County's 97.1% Good-day share places it cleaner than 96% of US counties in 2025.
- Closest median-AQI peer
- Beaverhead County (94.7% Good, median AQI 13) is the closest nationwide median-AQI peer to Teton County.
- 2024–2025 trend
- Teton County's floor-qualifying Good-day share is improving from 2024 to 2025 (92.3% → 97.1%).
- Median AQI
- Median AQI: 12
The verdict
According to EPA Air Quality System monitoring data, Teton County's air is good on balance, among the cleanest 5% of US counties, a median AQI of 12 with 97.1% of 277 monitored days in the Good band, driven mainly by PM2.5.
- 12
- median AQI · Good
- 97.1%
- days rated Good
- PM2.5
- main pollutant
- 96%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 92.
Annual release change
What changed in the 2025 EPA annual release
- Teton County's Good-day share rose from 92.3% to 97.1% between the 2024 and 2025 EPA annual releases, a change of +4.9 percentage points.
Data updated August 2026
- Good · 269 d · 97.1%
- Moderate · 8 d · 2.9%
How did Teton County's air break down in 2025?
Across 277 monitored days, 269 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 92 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 277 days monitored. Median AQI: 12 (Good).
Insights: Teton County, Montana. EPA monitors recorded a median Air Quality Index of 12 across 277 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 269 (97%) fell in the Good band (AQI 0–50), 8 (3%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 26, while the worst single-day peak hit 92 (Moderate). Residents averaged about 29.1 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (277 days). Across the 2024–2025 trend window, the share of monitored days rated Good shifted by +4.9 points (measured against 310 monitored days in 2024 and 277 in 2025, so raw day counts are not comparable) and the median AQI moved -1 points, placing the multi-year trajectory at improving. The worst single reading over the 2024–2025 window was AQI 92, moderate but never Unhealthy. Nearby counties show comparable readings: Beaverhead (94.7% good, AQI 13); Cascade (59.8% good, AQI 46); Custer (87.2% good, AQI 40); Dawson (90.3% good, AQI 18); Fergus (90.7% good, AQI 41); Flathead (73.7% good, AQI 41).
Air Quality Summary
Good Days
97.1%
269 of 277 monitored days
22.1pp vs 75% target
Max AQI Recorded
92
Moderate
Health Grade
Excellent
90th-pct AQI 26
Teton County, Good days share 97.1%
National avg
Share of monitored days at AQI 0-50 (Good band).
Teton 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 277 monitored days across EPA AQI categories.
Good
269
97%
Moderate
8
3%
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 Teton County.
- PM2.5 · 277 days · 100.0%
Health Impact Assessment
Excellent
Teton County's air quality is rated Excellent based on 97.1% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 97.1% of monitored days in 2025, with a median AQI of 12. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 277 of 277 monitored days.
5-Year Air Quality Trend
Air quality is improving in Teton County. Highest Good-day share: 2025 (97.1%, 269 of 277 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2024 | 286 | 23 | 1 | 0 | 13 | 101 |
| 2025 | 269 | 8 | 0 | 0 | 12 | 92 |
How does Teton County compare?
How Teton County compares
Good-day share better than typical
Teton County 97.1%
Beaverhead County, Montana 94.7%
Typical US county 76.0%
Median AQI better than typical
Teton County 12
Beaverhead County, Montana 13
Typical US county 39
Unhealthy days / yr better than typical
Teton County 0
Beaverhead County, Montana 0
Typical US county 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Teton County (12), not geographic neighbors.
Beaverhead County, Montana
Median AQI 13 · 94.7% Good-day share
Gallatin County, Montana
Median AQI 11 · 98.1% Good-day share
Navajo County, Arizona
Median AQI 13 · 99.5% Good-day share
Park County, Wyoming
Median AQI 13 · 98.0% Good-day share
Hill County, Montana
Median AQI 14 · 92.1% Good-day share
Lincoln County, Wyoming
Median AQI 10 · 98.9% 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).
Grays Harbor County, Washington
97.3% Good-day share · median AQI 22
Jefferson County, Washington
97.3% Good-day share · median AQI 20
Skagit County, Washington
97.5% Good-day share · median AQI 25
Blaine County, Idaho
96.6% Good-day share · median AQI 17
Washakie County, Wyoming
96.3% Good-day share · median AQI 8
Franklin County, Idaho
96.3% Good-day share · median AQI 21
Montana counties on the map
Geographic containment only, other monitored counties in Montana, independent of AQI or pollutant match.
What Teton 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 12 means for exposure. Health guidance
- See how Teton County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Teton County with its Montana neighbours before drawing a conclusion about the region. All of Montana
Based on 277 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 Teton County, Montana? ▼
Teton County has a median Air Quality Index (AQI) of 12, rated "Good." 97.1% of monitored days (269 out of 277) had good air quality in 2025.
What is the main pollutant in Teton County? ▼
The primary pollutant in Teton County is Fine Particles (PM2.5), which was the main AQI driver on 277 days (100% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Teton County have? ▼
In 2025, Teton County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 92.
Is the air quality in Teton County getting better or worse? ▼
Air quality in Teton County is improving across floor-qualifying years (2024-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2025 at 97.1% (269 of 277 days). Lowest qualifying Good-day share: 2024 at 92.3% (286 of 310 days).
What does AQI 12 mean for health? ▼
Teton County's median AQI of 12 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Teton County compare to other counties in Montana? ▼
Teton County has 97.1% good air days. Nearby counties in Montana: Beaverhead (94.7% good), Cascade (59.8% good), Custer (87.2% good), Dawson (90.3% good), Fergus (90.7% good), Flathead (73.7% good).
What is the 90th percentile AQI in Teton County? ▼
The 90th percentile AQI for Teton County is 26, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 92 (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. Spotted a figure that looks wrong? Report a correction.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for Teton County, Montana · 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.