Bad Air Days in Bayamon, Puerto Rico: 3 a Year
3 bad air days a year
About the middle of monitored US counties. Ranked 373 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly particles: smoke and dust (82% 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 October and May and June and September. Averaged over 2016 to 2025.
Is a purifier worth it 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
The worst recent year was 2018, with 13 bad days on 264 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2016-03-16 | 177 | Ozone |
| 2018-03-27 | 172 | PM2.5 |
| 2018-10-01 | 169 | PM2.5 |
| 2018-10-02 | 159 | PM2.5 |
| 2018-09-20 | 157 | PM2.5 |
The air on a normal day
Across 2,637 monitored days from 2016 to 2025, the air in Bayamon rated Good on 79% of them, more often than the 72% typical of monitored counties, and Moderate on 20%. The median day sat at AQI 26; one day in ten went above 52.
The pollutant setting the AQI on an ordinary day here:
- fine particles (PM2.5)51%1,344 days
- ozone25%659 days
- carbon monoxide24%634 days
Every recent year on file
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 164 | 141 | 21 | 2 | 0 | 29 | 102 |
| 2024 | 314 | 268 | 45 | 1 | 0 | 27 | 124 |
| 2023 | 216 | 193 | 23 | 0 | 0 | 22 | 74 |
| 2022 | 358 | 342 | 16 | 0 | 0 | 15 | 77 |
| 2021 | 347 | 320 | 27 | 0 | 0 | 10 | 77 |
| 2020 | 270 | 259 | 11 | 0 | 0 | 21 | 69 |
| 2019 | 278 | 239 | 39 | 0 | 0 | 20 | 79 |
| 2018 | 264 | 76 | 175 | 13 | 6 | 56 | 172 |
| 2017 | 159 | 46 | 109 | 4 | 0 | 60 | 132 |
| 2016 | 267 | 199 | 66 | 2 | 1 | 23 | 177 |
| 2015 | 267 | 241 | 25 | 1 | 0 | 18 | 146 |
| 2014 | 272 | 271 | 1 | 0 | 0 | 10 | 51 |
| 2013 | 357 | 351 | 5 | 1 | 0 | 9 | 106 |
| 2012 | 315 | 291 | 24 | 0 | 0 | 16 | 75 |
| 2011 | 223 | 222 | 1 | 0 | 0 | 6 | 66 |
| 2010 | 325 | 324 | 1 | 0 | 0 | 9 | 77 |
*2025 may be a partial year in EPA's file.
Elsewhere in Puerto Rico
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.