Bad Air Days in Monmouth County, New Jersey: 3 a Year
3 bad air days a year
About the middle of monitored US counties. Ranked 402 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 June and July and May. 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.
The worst days on file
In 2000 to 2009 this county averaged 19 bad days a year; in 2016 to 2025, 3. The air has improved. The worst recent year was 2025, with 6 bad days on 265 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2022-07-14 | 161 | Ozone |
| 2025-06-24 | 161 | Ozone |
| 2021-07-26 | 154 | Ozone |
| 2025-06-25 | 151 | Ozone |
| 2023-09-05 | 140 | Ozone |
An ordinary day in Monmouth
Across 2,484 monitored days from 2016 to 2025, the air in Monmouth County rated Good on 90% of them, more often than the 72% typical of monitored counties, and Moderate on 9%. The median day sat at AQI 36; one day in ten went above 52.
The pollutant setting the AQI on an ordinary day here:
- ozone100%2,484 days
Every recent year on file
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 265 | 242 | 17 | 6 | 2 | 36 | 161 |
| 2024 | 264 | 240 | 23 | 1 | 0 | 37 | 119 |
| 2023 | 247 | 210 | 35 | 2 | 0 | 39 | 140 |
| 2022 | 248 | 226 | 20 | 2 | 1 | 38 | 161 |
| 2021 | 255 | 227 | 24 | 4 | 1 | 36 | 154 |
| 2020 | 226 | 209 | 17 | 0 | 0 | 37 | 93 |
| 2019 | 240 | 217 | 23 | 0 | 0 | 37 | 100 |
| 2018 | 245 | 220 | 25 | 0 | 0 | 33 | 100 |
| 2017 | 258 | 245 | 12 | 1 | 0 | 31 | 101 |
| 2016 | 236 | 204 | 29 | 3 | 0 | 37 | 136 |
| 2015 | 236 | 189 | 41 | 6 | 1 | 41 | 154 |
| 2014 | 248 | 223 | 24 | 1 | 0 | 39 | 122 |
| 2013 | 249 | 203 | 42 | 4 | 1 | 40 | 151 |
| 2012 | 256 | 205 | 36 | 15 | 2 | 37 | 161 |
| 2011 | 309 | 268 | 31 | 10 | 2 | 36 | 179 |
| 2010 | 365 | 306 | 49 | 10 | 4 | 34 | 174 |
*2025 may be a partial year in EPA's file.
New Jersey compared
- Bergen County7/yr
- Mercer County6/yr
- Gloucester County6/yr
- Middlesex County5/yr
- Camden County5/yr
- Ocean County4/yr
- Hunterdon County3/yr
- Hudson County3/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.