Median AQI
14
Good
Wyoming · County air quality · 2025
Platte County, Wyoming
Median AQI 14 (Good). 87.7% of monitored days rated Good, direct from EPA Air Quality System stations.
- 14
- Median AQI
- 87.7%
- Good-air days
- 6
- Unhealthy days
- 71%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Platte County's air is good on balance, cleaner than the median US county, a median AQI of 14 with 87.7% of 179 monitored days in the Good band, driven mainly by PM10.
- 14
- median AQI · Good
- 87.7%
- days rated Good
- PM10
- main pollutant
- 71%
- cleaner than US counties
6 days reached Unhealthy or worse; the worst single reading hit AQI 406.
Data updated July 2026
- Good · 157 d · 87.7%
- Moderate · 14 d · 7.8%
- USG · 2 d · 1.1%
- Unhealthy · 3 d · 1.7%
- Very Unhealthy · 2 d · 1.1%
- Hazardous · 1 d · 0.6%
How did Platte County's air break down in 2025?
Across 179 monitored days, 157 fell in the Good band (AQI 0–50) and 6 reached Unhealthy or worse. The worst single day peaked at AQI 406 (Hazardous).
EPA AQS →Air quality data from EPA Air Quality System (2025). 179 days monitored. Median AQI: 14 (Good).
Insights: Platte County, Wyoming. EPA monitors recorded a median Air Quality Index of 14 across 179 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 157 (88%) fell in the Good band (AQI 0–50), 14 (8%) registered Moderate readings, and 2 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 59, while the worst single-day peak hit 406 (Hazardous). Residents averaged about 26.3 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM10 (179 days). Across the 2020–2025 trend window, good days shifted by -45 and the median AQI moved -5 points, placing the multi-year trajectory at stable. Residents and visitors experienced 6 unhealthy-or-worse days combined, periods when the EPA recommends sensitive groups limit prolonged outdoor exertion. Nearby counties show comparable readings: Albany (51.9% good, AQI 50); Campbell (77.3% good, AQI 43); Carbon (100.0% good, AQI 7); Converse (94.5% good, AQI 41); Fremont (61.3% good, AQI 48); Johnson (90.6% good, AQI 42).
Air Quality Summary
Good Days
87.7%
157 of 179 monitored days
12.7pp vs 75% target
Max AQI Recorded
406
Hazardous
Health Grade
Good
90th-pct AQI 59
Platte County, Good days share 87.7%
National avg
Share of monitored days at AQI 0-50 (Good band).
Platte County, Unhealthy-or-worse share 3.4%
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
157
88%
Moderate
14
8%
USG
2
1%
Unhealthy
3
2%
Very Unhealthy
2
1%
Hazardous
1
1%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Platte County.
- PM10 · 179 days · 100.0%
Health Impact Assessment
Good
Platte County's air quality is rated Good based on 87.7% good air days. There were 6 unhealthy days in 2025 when outdoor activity should be limited.
Air quality posed significant health risk in 2025. Sensitive groups, including people with asthma, COPD, cardiovascular conditions, children, pregnant women, and adults over 65, should monitor AirNow.gov alerts and limit outdoor activity on Unhealthy (AQI 151+) and Very Unhealthy (201+) days. Peak readings reached AQI 406, well into the Hazardous range.
Sensitive group advisory
People with asthma, COPD, heart disease, children, pregnant women, and adults 65+ should follow EPA AQI alerts daily and limit outdoor exertion when AQI exceeds 100. Real-time conditions: airnow.gov.
The dominant pollutant is PM10, driving AQI on 179 of 179 monitored days.
5-Year Air Quality Trend
Air quality is stable in Platte County. Best year: 2023 (334 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 202 | 20 | 1 | 0 | 19 | 283 |
| 2021 | 324 | 28 | 2 | 3 | 16 | 682 |
| 2022 | 311 | 29 | 8 | 3 | 17 | 692 |
| 2023 | 334 | 25 | 1 | 3 | 14 | 320 |
| 2024 | 325 | 32 | 6 | 1 | 19 | 927 |
| 2025 | 157 | 14 | 2 | 3 | 14 | 406 |
How does Platte County compare?
How Platte County compares
Good-day share better than US avg
Platte County 87.7%
Albany County, Wyoming 51.9%
US average 76.5%
Median AQI better than US avg
Platte County 14
Albany County, Wyoming 50
US average 38
Unhealthy days / yr worse than US avg
Platte County 6
Albany County, Wyoming 0
US average 0
Other Counties in Wyoming
Air quality comparison for nearby counties in Wyoming.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Platte County.
Apache County, Arizona
AQI 14 · 99.6% good
Dawson County, Montana
AQI 14 · 95.0% good
Gallatin County, Montana
AQI 14 · 99.1% good
Hughes County, South Dakota
AQI 14 · 94.4% good
Klickitat County, Washington
AQI 14 · 84.2% good
Park County, Wyoming
AQI 14 · 99.5% good
What Platte County's air means for you
On most days the air here is fine, but PM10 drives 6 unhealthy-or-worse days a year that sensitive groups should plan around.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-PM10 days, the guide explains what a median of 14 means for exposure. Health guidance
- See how Platte County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Platte County with its Wyoming neighbours before drawing a conclusion about the region. All of Wyoming
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 Platte County, Wyoming? ▼
Platte County has a median Air Quality Index (AQI) of 14, rated "Good." 87.7% of monitored days (157 out of 179) had good air quality in 2025.
What is the main pollutant in Platte County? ▼
The primary pollutant in Platte County is Coarse Particles (PM10), which was the main AQI driver on 179 days (100% of monitored days). Irritates airways and can aggravate asthma and bronchitis.
How many unhealthy air days does Platte County have? ▼
In 2025, Platte County recorded 6 unhealthy air days (3 Unhealthy, 2 Very Unhealthy, 1 Hazardous). The maximum AQI reached 406.
Is the air quality in Platte County getting better or worse? ▼
Air quality in Platte County is stable based on 5-year trends (2020-2025). Best year: 2023 with 334 good days. Worst year: 2025 with 157 good days.
What does AQI 14 mean for health? ▼
Platte County's median AQI of 14 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 Platte County compare to other counties in Wyoming? ▼
Platte County has 87.7% good air days. Nearby counties in Wyoming: Albany (51.9% good), Campbell (77.3% good), Carbon (100.0% good), Converse (94.5% good), Fremont (61.3% good), Johnson (90.6% good).
What is the 90th percentile AQI in Platte County? ▼
The 90th percentile AQI for Platte County is 59, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 406 (Hazardous).
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.