Median AQI
42
Good
Nevada · County air quality · 2025
Carson City County, Nevada
Median AQI 42 (Good). 86.2% of monitored days rated Good, direct from EPA Air Quality System stations.
- 42
- Median AQI
- 86.2%
- Good-air days
- 0
- Unhealthy days
- 73%
- Cleaner than US counties
Carson City County's 2025 annual median AQI is 42 (Good), with 86.2% Good days
According to the U.S. EPA Air Quality System, Carson City County, Nevada posted a 2025 median AQI of 42 (Good) across 363 monitored days, with 86.2% 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
- Carson City County's 86.2% Good-day share places it cleaner than 73% of US counties in 2025.
- Closest median-AQI peer
- Ada County (74.0% Good, median AQI 42) is the closest nationwide median-AQI peer to Carson City County.
- 2020–2025 trend
- Carson City County's floor-qualifying Good-day share is improving from 2020 to 2025 (78.0% → 86.2%).
- Median AQI
- Median AQI: 42
The verdict
According to EPA Air Quality System monitoring data, Carson City County's air is good on balance, cleaner than the median US county, a median AQI of 42 with 86.2% of 363 monitored days in the Good band, driven mainly by Ozone.
- 42
- median AQI · Good
- 86.2%
- days rated Good
- Ozone
- main pollutant
- 73%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 80.
Annual release change
What changed in the 2025 EPA annual release
- Carson City County's Good-day share rose from 73.8% to 86.2% between the 2024 and 2025 EPA annual releases, a change of +12.5 percentage points.
- Carson City County's peak single-day AQI fell from 105 to 80 between the 2024 and 2025 EPA annual releases, a change of -25 points.
- Carson City County's median AQI fell from 45 to 42 between the 2024 and 2025 EPA annual releases, a change of -3 points.
Data updated August 2026
- Good · 313 d · 86.2%
- Moderate · 50 d · 13.8%
How did Carson City County's air break down in 2025?
Across 363 monitored days, 313 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 80 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 363 days monitored. Median AQI: 42 (Good).
Insights: Carson City County, Nevada. EPA monitors recorded a median Air Quality Index of 42 across 363 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 313 (86%) fell in the Good band (AQI 0–50), 50 (14%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 52, while the worst single-day peak hit 80 (Moderate). Residents averaged about 25.9 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (268 days), PM2.5 (95 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by +8.6 points and the median AQI moved +0 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 80, moderate but never Unhealthy. Nearby counties show comparable readings: Churchill (85.2% good, AQI 40); Clark (31.0% good, AQI 61); Douglas (91.1% good, AQI 22); Elko (86.3% good, AQI 42); Lyon (90.0% good, AQI 41); Nye (92.6% good, AQI 26).
Air Quality Summary
Good Days
86.2%
313 of 363 monitored days
11.2pp vs 75% target
Max AQI Recorded
80
Moderate
Health Grade
Good
90th-pct AQI 52
Carson City County, Good days share 86.2%
National avg
Share of monitored days at AQI 0-50 (Good band).
Carson City 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 363 monitored days across EPA AQI categories.
Good
313
86%
Moderate
50
14%
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 Carson City County.
- Ozone · 268 days · 73.8%
- PM2.5 · 95 days · 26.2%
Health Impact Assessment
Good
Carson City County's air quality is rated Good based on 86.2% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 86.2% of monitored days in 2025, with a median AQI of 42. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 268 of 363 monitored days.
5-Year Air Quality Trend
Air quality is improving in Carson City County. Highest Good-day share: 2025 (86.2%, 313 of 363 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 284 | 62 | 12 | 6 | 42 | 210 |
| 2021 | 273 | 64 | 9 | 12 | 42 | 304 |
| 2022 | 290 | 65 | 5 | 2 | 44 | 227 |
| 2023 | 236 | 126 | 1 | 0 | 47 | 105 |
| 2024 | 270 | 95 | 1 | 0 | 45 | 105 |
| 2025 | 313 | 50 | 0 | 0 | 42 | 80 |
How does Carson City County compare?
How Carson City County compares
Good-day share better than typical
Carson City County 86.2%
Ada County, Idaho 74.0%
Typical US county 76.0%
Median AQI worse than typical
Carson City County 42
Ada County, Idaho 42
Typical US county 39
Unhealthy days / yr better than typical
Carson City County 0
Ada County, Idaho 0
Typical US county 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Carson City County (42), not geographic neighbors.
Ada County, Idaho
Median AQI 42 · 74.0% Good-day share
Adams County, Pennsylvania
Median AQI 42 · 74.4% Good-day share
Allen County, Ohio
Median AQI 42 · 67.0% Good-day share
Asotin County, Washington
Median AQI 42 · 61.9% Good-day share
Baldwin County, Alabama
Median AQI 42 · 75.5% Good-day share
Bell County, Kentucky
Median AQI 42 · 67.0% Good-day share
Same primary pollutant: Ozone
Ozone 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).
Apache County, Arizona
86.2% Good-day share · median AQI 33
Elko County, Nevada
86.3% Good-day share · median AQI 42
Bucks County, Pennsylvania
86.2% Good-day share · median AQI 36
Natrona County, Wyoming
86.3% Good-day share · median AQI 42
Yellowstone County, Montana
86.3% Good-day share · median AQI 38
Dorchester County, Maryland
86.0% Good-day share · median AQI 39
Nevada counties on the map
Geographic containment only, other monitored counties in Nevada, independent of AQI or pollutant match.
What Carson City County's air means for you
The air here stays in the breathable range year-round, with Ozone the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-Ozone days, the guide explains what a median of 42 means for exposure. Health guidance
- See how Carson City County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Carson City County with its Nevada neighbours before drawing a conclusion about the region. All of Nevada
Based on 363 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 Carson City County, Nevada? ▼
Carson City County has a median Air Quality Index (AQI) of 42, rated "Good." 86.2% of monitored days (313 out of 363) had good air quality in 2025.
What is the main pollutant in Carson City County? ▼
The primary pollutant in Carson City County is Ozone (O3), which was the main AQI driver on 268 days (74% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Carson City County have? ▼
In 2025, Carson City County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 80.
Is the air quality in Carson City County getting better or worse? ▼
Air quality in Carson City 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 86.2% (313 of 363 days). Lowest qualifying Good-day share: 2023 at 65.0% (236 of 363 days).
What does AQI 42 mean for health? ▼
Carson City County's median AQI of 42 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Carson City County compare to other counties in Nevada? ▼
Carson City County has 86.2% good air days. Nearby counties in Nevada: Churchill (85.2% good), Clark (31.0% good), Douglas (91.1% good), Elko (86.3% good), Lyon (90.0% good), Nye (92.6% good).
What is the 90th percentile AQI in Carson City County? ▼
The 90th percentile AQI for Carson City County is 52, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 80 (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 Carson City County, Nevada · 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.