Bad Air Days in New London County, Connecticut: 7 a Year
7 bad air days a year
More bad air days than three quarters of monitored counties. Ranked 140 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly ozone: summer smog (9% particle days).
The bad-air season here
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Most bad days here fall in July and June and August. Averaged over 2016 to 2025.
Is a purifier worth it here?
- 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.
Better or worse than it was
In 2000 to 2009 this county averaged 19 bad days a year; in 2016 to 2025, 7. The air has improved. The worst recent year was 2016, with 10 bad days on 357 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2020-07-30 | 172 | Ozone |
| 2023-06-08 | 166 | PM2.5 |
| 2017-05-18 | 161 | Ozone |
| 2017-06-13 | 161 | Ozone |
| 2023-06-07 | 160 | PM2.5 |
An ordinary day in New London
Across 3,569 monitored days from 2016 to 2025, the air in New London County rated Good on 79% of them, more often than the 72% typical of monitored counties, and Moderate on 19%. The median day sat at AQI 39; one day in ten went above 58.
The pollutant setting the AQI on an ordinary day here:
- fine particles (PM2.5)55%1,962 days
- ozone45%1,607 days
Every recent year on file
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 364 | 296 | 60 | 8 | 0 | 38 | 136 |
| 2024 | 365 | 309 | 51 | 5 | 0 | 37 | 126 |
| 2023 | 363 | 258 | 95 | 10 | 3 | 41 | 166 |
| 2022 | 365 | 290 | 71 | 4 | 0 | 39 | 108 |
| 2021 | 363 | 277 | 79 | 7 | 0 | 39 | 129 |
| 2020 | 365 | 274 | 87 | 4 | 1 | 41 | 172 |
| 2019 | 364 | 295 | 62 | 7 | 0 | 40 | 129 |
| 2018 | 315 | 260 | 49 | 6 | 0 | 39 | 140 |
| 2017 | 348 | 286 | 54 | 8 | 2 | 39 | 161 |
| 2016 | 357 | 282 | 65 | 10 | 1 | 38 | 154 |
| 2015 | 359 | 265 | 82 | 12 | 1 | 40 | 151 |
| 2014 | 355 | 236 | 118 | 1 | 0 | 43 | 104 |
| 2013 | 349 | 125 | 217 | 7 | 3 | 53 | 164 |
| 2012 | 339 | 166 | 159 | 14 | 4 | 51 | 197 |
| 2011 | 238 | 167 | 60 | 11 | 1 | 42 | 156 |
| 2010 | 364 | 245 | 111 | 8 | 0 | 41 | 126 |
*2025 may be a partial year in EPA's file.
Elsewhere in Connecticut
- Fairfield County20/yr
- Middlesex County13/yr
- New Haven County12/yr
- Tolland County6/yr
- Hartford County5/yr
- Litchfield County4/yr
- Windham 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.