Bad Air Days in Cecil County, Maryland: 4 a Year
4 bad air days a year
About the middle of monitored US counties. Ranked 251 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly ozone: summer smog (14% 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 and May and September. Averaged over 2016 to 2025.
What to buy, and what not to
- Ozone drives many bad days here. Purifiers and filters do not remove ozone, so do not buy one for that. Ozone peaks on hot afternoons: exercise outside in the morning.
The worst days on file
In 2000 to 2009 this county averaged 36 bad days a year; in 2016 to 2025, 4. The air has improved. The worst recent year was 2016, with 10 bad days on 359 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2023-06-07 | 190 | PM2.5 |
| 2023-06-08 | 189 | PM2.5 |
| 2023-06-29 | 166 | PM2.5 |
| 2017-05-18 | 161 | Ozone |
| 2016-07-22 | 154 | Ozone |
Most days, not the worst ones
Across 3,595 monitored days from 2016 to 2025, the air in Cecil County rated Good on 70% of them, close to the 72% typical of monitored counties, and Moderate on 29%. The median day sat at AQI 43; one day in ten went above 62.
The pollutant setting the AQI on an ordinary day here:
- fine particles (PM2.5)52%1,862 days
- ozone48%1,733 days
Cecil County by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 361 | 288 | 71 | 2 | 0 | 41 | 129 |
| 2024 | 360 | 236 | 121 | 3 | 0 | 44 | 126 |
| 2023 | 360 | 266 | 88 | 6 | 4 | 42 | 190 |
| 2022 | 361 | 267 | 93 | 1 | 0 | 43 | 101 |
| 2021 | 358 | 235 | 119 | 4 | 0 | 44 | 118 |
| 2020 | 357 | 309 | 48 | 0 | 0 | 38 | 97 |
| 2019 | 361 | 265 | 93 | 3 | 0 | 42 | 150 |
| 2018 | 358 | 207 | 144 | 7 | 0 | 47 | 129 |
| 2017 | 360 | 222 | 130 | 8 | 1 | 45 | 161 |
| 2016 | 359 | 209 | 140 | 10 | 1 | 47 | 154 |
| 2015 | 358 | 180 | 173 | 5 | 1 | 50 | 187 |
| 2014 | 347 | 193 | 149 | 5 | 0 | 47 | 150 |
| 2013 | 357 | 188 | 164 | 5 | 0 | 49 | 143 |
| 2012 | 360 | 180 | 156 | 24 | 5 | 51 | 172 |
| 2011 | 357 | 167 | 178 | 12 | 6 | 52 | 177 |
| 2010 | 353 | 168 | 163 | 22 | 2 | 52 | 161 |
*2025 may be a partial year in EPA's file.
Nearby counties on file
- Baltimore County8/yr
- Harford County7/yr
- Anne Arundel County5/yr
- Prince George's County5/yr
- Baltimore City4/yr
- Kent County2/yr
- Frederick County2/yr
- Charles County2/yr
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, and on why a purifier does not touch ozone in smoke vs ozone.