Bad Air Days in Tolland County, Connecticut: 6 a Year
6 bad air days a year
More bad air days than three quarters of monitored counties. Ranked 181 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly ozone: summer smog (0% 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 May and June and July and August. Averaged over 2016 to 2025.
What actually helps 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.
The record for Tolland
The worst recent year was 2016, with 5 bad days on 176 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2023-04-14 | 156 | Ozone |
| 2024-06-20 | 156 | Ozone |
| 2017-05-17 | 147 | Ozone |
| 2016-05-26 | 140 | Ozone |
| 2018-06-18 | 140 | Ozone |
An ordinary day in Tolland
Across 2,053 monitored days from 2016 to 2025, the air in Tolland County rated Good on 87% of them, more often than the 72% typical of monitored counties, and Moderate on 11%. The median day sat at AQI 39; one day in ten went above 56.
The pollutant setting the AQI on an ordinary day here:
- ozone100%2,053 days
Tolland County by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 209 | 175 | 29 | 5 | 0 | 40 | 136 |
| 2024 | 205 | 184 | 16 | 5 | 1 | 37 | 156 |
| 2023 | 212 | 178 | 31 | 3 | 1 | 41 | 156 |
| 2022 | 208 | 187 | 19 | 2 | 0 | 39 | 122 |
| 2021 | 201 | 170 | 30 | 1 | 0 | 39 | 101 |
| 2020 | 206 | 192 | 14 | 0 | 0 | 39 | 93 |
| 2019 | 212 | 187 | 20 | 5 | 0 | 42 | 126 |
| 2018 | 213 | 189 | 20 | 4 | 0 | 38 | 140 |
| 2017 | 211 | 188 | 20 | 3 | 0 | 39 | 147 |
| 2016 | 176 | 144 | 27 | 5 | 0 | 41 | 140 |
| 2015 | 183 | 154 | 23 | 6 | 0 | 39 | 129 |
| 2014 | 178 | 141 | 28 | 9 | 0 | 41 | 140 |
| 2013 | 172 | 134 | 31 | 7 | 0 | 41 | 147 |
| 2012 | 181 | 125 | 37 | 19 | 2 | 44 | 177 |
| 2011 | 167 | 145 | 19 | 3 | 1 | 39 | 154 |
| 2010 | 181 | 129 | 37 | 15 | 2 | 43 | 190 |
*2025 may be a partial year in EPA's file.
Elsewhere in Connecticut
- Fairfield County20/yr
- Middlesex County13/yr
- New Haven County12/yr
- New London County7/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.