Bad Air Days in Marshall County, West Virginia: under 1 a Year
under 1 bad air day a year
Rare: among the cleanest-air counties EPA monitors. Ranked 809 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly particles: smoke and dust (100% particle days).
Which months to watch
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Most bad days here fall in June and July. Averaged over 2016 to 2025.
What actually helps here
- Bad air days are rare here. A standard furnace filter is enough; no purifier needed for outdoor air.
- On the odd bad day, check AirNow and keep windows shut.
Better or worse than it was
In 2000 to 2009 this county averaged 8 bad days a year; in 2016 to 2025, under 1. The air has improved. The worst recent year was 2023, with 3 bad days on 354 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2023-06-28 | 213 | PM2.5 |
| 2023-06-29 | 193 | PM2.5 |
| 2021-07-20 | 121 | PM2.5 |
| 2023-07-17 | 108 | PM2.5 |
| 2022-01-31 | 99 | PM2.5 |
Most days, not the worst ones
Across 2,847 monitored days from 2016 to 2025, the air in Marshall County rated Good on 50% of them, less often than the 72% typical of monitored counties, and Moderate on 49%. The median day sat at AQI 49; one day in ten went above 66.
The pollutant setting the AQI on an ordinary day here:
- fine particles (PM2.5)100%2,847 days
Year by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 284 | 181 | 103 | 0 | 0 | 42 | 81 |
| 2024 | 359 | 267 | 92 | 0 | 0 | 39 | 81 |
| 2023 | 354 | 149 | 202 | 3 | 2 | 52 | 213 |
| 2022 | 361 | 162 | 199 | 0 | 0 | 52 | 99 |
| 2021 | 353 | 140 | 212 | 1 | 0 | 53 | 121 |
| 2020 | 118 | 87 | 31 | 0 | 0 | 41 | 72 |
| 2019 | 118 | 68 | 50 | 0 | 0 | 46 | 80 |
| 2018 | 229 | 99 | 130 | 0 | 0 | 52 | 94 |
| 2017 | 365 | 116 | 249 | 0 | 0 | 55 | 85 |
| 2016 | 306 | 167 | 139 | 0 | 0 | 48 | 86 |
| 2015 | 363 | 176 | 187 | 0 | 0 | 51 | 88 |
| 2014 | 362 | 137 | 225 | 0 | 0 | 54 | 84 |
| 2013 | 365 | 143 | 222 | 0 | 0 | 54 | 91 |
| 2012 | 364 | 102 | 262 | 0 | 0 | 57 | 87 |
| 2011 | 351 | 122 | 228 | 1 | 0 | 55 | 106 |
| 2010 | 350 | 97 | 250 | 3 | 0 | 58 | 112 |
*2025 may be a partial year in EPA's file.
Elsewhere in West Virginia
- Ohio County1/yr
- Berkeley County1/yr
- Hancock Countyunder 1/yr
- Wood Countyunder 1/yr
- Kanawha Countyunder 1/yr
- Cabell Countyunder 1/yr
- Brooke Countyunder 1/yr
- Marion Countythin data
How this is counted
A bad air day is a day the county's daily AQI from EPA AirData went above 100, the level where EPA tells children, older adults and people with asthma or heart disease to cut back outdoors. Monitors do not run every day, so yearly counts are scaled to 365 days. This is the record, not today's air: for that, check AirNow. More on the method in how the county numbers are made, on the AQI 100 line in what counts as a bad air day.