Bad Air Days in Hillsborough County, Florida: 3 a Year
3 bad air days a year
About the middle of monitored US counties. Ranked 387 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly ozone: summer smog (10% particle days).
When the bad days come in Hillsborough
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Most bad days here fall in May and April. Averaged over 2016 to 2025.
What to buy, and what not to
- 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.
The worst days on file
In 2000 to 2009 this county averaged 22 bad days a year; in 2016 to 2025, 3. The air has improved. The worst recent year was 2019, with 5 bad days on 365 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2016-05-24 | 154 | Ozone |
| 2017-05-10 | 150 | Ozone |
| 2024-05-30 | 143 | Ozone |
| 2017-05-09 | 129 | Ozone |
| 2017-05-11 | 129 | Ozone |
Most days, not the worst ones
Across 3,644 monitored days from 2016 to 2025, the air in Hillsborough County rated Good on 49% of them, less often than the 72% typical of monitored counties, and Moderate on 51%. The median day sat at AQI 51; one day in ten went above 65.
The pollutant setting the AQI on an ordinary day here:
- fine particles (PM2.5)74%2,688 days
- ozone26%943 days
Year by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 365 | 194 | 169 | 2 | 0 | 49 | 122 |
| 2024 | 362 | 190 | 168 | 4 | 0 | 50 | 143 |
| 2023 | 365 | 156 | 206 | 3 | 0 | 51 | 114 |
| 2022 | 365 | 175 | 189 | 1 | 0 | 51 | 126 |
| 2021 | 365 | 167 | 197 | 1 | 0 | 51 | 129 |
| 2020 | 366 | 176 | 187 | 3 | 0 | 52 | 112 |
| 2019 | 365 | 202 | 158 | 5 | 0 | 49 | 126 |
| 2018 | 365 | 168 | 193 | 4 | 0 | 51 | 122 |
| 2017 | 360 | 167 | 190 | 3 | 0 | 52 | 150 |
| 2016 | 366 | 178 | 185 | 3 | 1 | 51 | 154 |
| 2015 | 365 | 161 | 203 | 1 | 0 | 52 | 119 |
| 2014 | 365 | 157 | 202 | 6 | 0 | 52 | 115 |
| 2013 | 365 | 171 | 191 | 3 | 0 | 51 | 122 |
| 2012 | 366 | 136 | 221 | 9 | 0 | 53 | 147 |
| 2011 | 365 | 135 | 216 | 14 | 0 | 53 | 143 |
| 2010 | 365 | 108 | 247 | 10 | 1 | 55 | 154 |
*2025 may be a partial year in EPA's file.
Nearby counties on file
- Miami-Dade County3/yr
- Duval County2/yr
- Broward County1/yr
- Osceola County1/yr
- Orange Countyunder 1/yr
- Polk Countyunder 1/yr
- Pinellas Countyunder 1/yr
- Seminole Countyunder 1/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.