What Is the Air Quality in San Juan, Puerto Rico?

San Juan, Puerto Rico earns an A — it is among the cleanest U.S. cities tracked by EPA monitoring, with median AQI averaging just 10 over the past five years. Days in the "Good" category dominate the calendar; air-quality alerts are rare.

San Juan, Puerto Rico's 5-year median AQI of 10 is 31 points below the national average of 41 — meaningfully cleaner than the typical U.S. metro tracked here. Within Puerto Rico, San Juan, Puerto Rico runs cleaner than the state average of 23 — a positive signal that local conditions (terrain, wind patterns, emission sources) are working in residents' favor.

For context within Puerto Rico: Caguas, Puerto Rico currently holds the state's cleanest grade (A, AQI 10), while Catano, Puerto Rico sits at the bottom (D, AQI 42).

Air quality in San Juan, Puerto Rico has been improving over the past decade, with median AQI dropping by roughly 1.1 points per year. That is consistent with the broader national pattern — most U.S. metros have seen steady reductions in particulate and ozone pollution since the 2010s as cleaner vehicles and power plants come online.

In 2014, San Juan, Puerto Rico posted a median AQI of 17. By 2021 that figure was 7 — a drop of 10 AQI points cleaner across 7 years of EPA records.

Across the past five years, this area has logged just 0 days where AQI rose into the "Unhealthy for Sensitive Groups" range or worse — about 0 days per year, or roughly one every other month. That is a low count by national standards.

For most healthy adults, current air quality in this area does not require any change in behavior. People with severe asthma, COPD, or recent cardiac events should still keep an eye on daily AQI alerts, especially during wildfire season. Day-to-day exposure can vary significantly within a single metro — sign up for AirNow.gov alerts at your specific zip code rather than relying on the city-level number.