State air quality · 2025
Mississippi Air Quality Ranking
Across 10 monitored counties, the typical county in Mississippi posts a median AQI of 42 (Good) and 72.9% of monitored days were rated Good, from EPA AQS.
- 42
- Avg median AQI
- 72.9%
- Good-air days
- 10
- Counties monitored
- 29%
- Cleaner than US states
Mississippi's typical county median AQI is 42 (Good) across 10 monitored counties
According to the U.S. EPA Air Quality System, Mississippi monitors 10 counties with a day-weighted Good-day share of 72.9%. Cleanest: Yalobusha County (96.6% Good). Most polluted: Hinds County (45.8%). These are annual summaries, not live AirNow readings.
Data source EPA Air Quality System (AQS)
- Cleaner than US states
- Mississippi's day-weighted Good-day share of 72.9% places it cleaner than 29% of US states.
- In-state spread
- Within Mississippi, Yalobusha County leads at 96.6% Good days while Hinds County sits at 45.8% across 10 monitored counties.
- 2024→2025 release
- Mississippi's Good-day share moved +2.8 points vs the 2024 EPA annual release.
- Typical median AQI
- Typical median AQI: 42
Verify with AirNow → · EPA AQS →
EPA state monitoring brief
AQS state key MISSISSIPPI
Mississippi · 2025 EPA AQS · 10 counties · med AQI 42 · 72.9% Good · Yalobusha→Hinds spread
- GOOD 42 Median AQI · Good
- SHARE 72.9% Good-day share
- COUNT 10 Counties monitored
- UNH 0 Unhealthy+ days
- RANK 29% Cleaner than states
- PM25 55.1% Main pollutant share
Good-day share peers
Mississippi's 72.9% Good-day share is cleaner than 29% of monitored US states; Yalobusha and Hinds County bracket the in-state range. Open Yalobusha County →
According to EPA AQS annual summaries on PlainAirData, Mississippi ranks #37 of 52 by day-weighted good-day share (72.9%) and #42 by mean county median AQI (42.0). Hawaii is #1 of 52 by day-weighted good-day share (93.8% of monitored days) at mean county median-AQI #4 (27.3) ≠ Alaska #1 lowest mean county median AQI (20.3) at good-day share #8 (84.4%).
Data updated August 2026
What changed, what drives it, and how thick is the sample
Three derived views WPR-style word count does not substitute for: release-over-release movement from county annual rows, the EPA main-pollutant day mix, and how many counties sit below the 100-day ranking floor.
Release change
72.9%
Good-day share in 2025, up 2.8 percentage points vs 2024. County-mean median AQI 42, 1.0 points lower (cleaner) than 2024.
Pollutant mix
PM2.5
Main driver on 55.1% of pollutant-assigned days.
- PM2.5 55.1%
- Ozone 44.8%
Monitoring coverage
338
Average monitored days per county in the latest release. Every monitored county clears the 100-day ranking floor.
Counties Monitored
10
Good Days %
72.9%
Avg Median AQI
42
Total Unhealthy Days
0
Best Air Quality
Yalobusha County
Worst Air Quality
Hinds County
Where Mississippi sits nationally
COUNT-derived placement among 52 US states with at least 365 monitored days in the latest county release. Mississippi's day-weighted Good-day share is 72.9% - cleaner than 29% of that comparison set.
Mississippi Good-day share vs. every US state
Day-weighted share of monitored days in the Good band (AQI 0–50) - EPA AQS annual release
72.9% 29th percentile higher than 29% of 52 US states
Each bar is a band; taller bars hold more US states. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.
Source U.S. Environmental Protection Agency, Air Quality System (AQS) · 2025
Which counties in Mississippi have the cleanest and most polluted air?
Cleanest counties in Mississippi
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025. See our methodology for how AQI and median figures are computed.
Coverage: 10 counties in Mississippi with active monitoring stations. Unmonitored counties are not represented.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files, aggregated to the state level · 2020–2025
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.
Informational only, not professional advice. Data from EPA AQS. See our disclaimer.