San Juan, Puerto Rico Air Quality
San Juan air quality today — the AQI, the main pollutant, and whether it’s safe to exercise outside right now
San Juan, PR · Air quality right now
The air quality index in San Juan, PR is 17 (Good) right now — safe for outdoor activity.
Is it safe to be outside in San Juan today?
AQI 17 Yes — air quality is Good
Air is clean — great for outdoor activity.Main pollutant: OzoneObserved 1:00 AM AST
Pollutants right now
- PM2.55.7 µg/m³fine particles — smoke, exhaust, soot
- PM106.8 µg/m³coarse particles — dust, pollen, ash
- Ozone33 µg/m³Main pollutantsmog — builds on hot, sunny days
- NO₂2.1 µg/m³nitrogen dioxide — traffic, combustion
ExerciseOK to run — no air-quality limits on outdoor exercise.
How to read San Juan’s air quality
Guides: The AQI Scale, Explained · Air Quality Alerts, Decoded · How to Read a Wildfire Smoke Map · Why Wildfire Smoke Travels 1,000 Miles.
Air quality over time in San Juan
Across the EPA’s county records from 2020 to 2021, San Juan’s cleanest year was 2021 (median AQI 7) and its most polluted was 2020 (median AQI 9); the typical (median) day has trended cleaner since 2020.
| Year | Median AQI | Unhealthy+ | Main pollutant | USG | Moderate | Good |
|---|---|---|---|---|---|---|
| 2020 | 9 | 0 | CO | 0 | 0 | 216 |
| 2021 | 7 | 0 | CO | 0 | 0 | 41 |
“USG” is Unhealthy for Sensitive Groups (AQI 101–150); “Unhealthy+” combines the Unhealthy, Very Unhealthy, and Hazardous days. In 2024 the EPA tightened the annual fine-particle (PM2.5) standard to 9 µg/m³ from the previous 12 µg/m³, so counties near the old limit read worse against the new one. Source: EPA AQS annual summaries, 2020–2021.
Frequently asked
- What was the worst year for air quality in San Juan?
- No day in San Juan's county topped AQI 100 in the EPA's 2020–2021 records. The highest median AQI came in 2020, at 9.
- How many unhealthy air days does San Juan have?
- None: across 2020–2021, no day in San Juan's county had an AQI above 100 in the EPA's records (257 days reported).
- What's the main air pollutant in San Juan?
- CO: it drove San Juan's county AQI on the most days in every year of the EPA's 2020–2021 records.