Bad Air Days in Mayagnez, Puerto Rico: 3 a Year
3 bad air days a year
About the middle of monitored US counties. Ranked 410 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly particles: smoke and dust (60% 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 August and June. 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.
Better or worse than it was
The worst recent year was 2025, with 4 bad days on 227 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2020-08-24 | 396 | Ozone |
| 2025-05-18 | 350 | Ozone |
| 2025-05-19 | 300 | Ozone |
| 2020-08-04 | 248 | Ozone |
| 2020-08-31 | 165 | PM2.5 |
An ordinary day in Mayagnez
Across 2,029 monitored days from 2019 to 2025, the air in Mayagnez rated Good on 83% of them, more often than the 72% typical of monitored counties, and Moderate on 16%. The median day sat at AQI 25; one day in ten went above 49.
The pollutant setting the AQI on an ordinary day here:
- fine particles (PM2.5)58%1,186 days
- ozone42%843 days
Year by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 227 | 222 | 1 | 4 | 2 | 9 | 350 |
| 2024 | 341 | 341 | 0 | 0 | 0 | 11 | 39 |
| 2023 | 285 | 254 | 31 | 0 | 0 | 25 | 64 |
| 2022 | 321 | 235 | 81 | 5 | 1 | 38 | 155 |
| 2021 | 334 | 231 | 101 | 2 | 0 | 38 | 142 |
| 2020 | 319 | 266 | 49 | 4 | 3 | 22 | 396 |
| 2019 | 202 | 136 | 66 | 0 | 0 | 33 | 87 |
| 2014 | 9 | 8 | 1 | 0 | 0 | 23 | 53 |
| 2013 | 81 | 75 | 6 | 0 | 0 | 26 | 60 |
| 2012 | 115 | 93 | 22 | 0 | 0 | 27 | 76 |
| 2011 | 67 | 60 | 7 | 0 | 0 | 27 | 61 |
*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.