San Juan, Puerto Rico Air Quality
San Juan County, Puerto Rico (PR)
↓ Improvingover 7 years
How San Juan, Puerto Rico Air Quality Compares
San Juan, Puerto Rico's median AQI of 7is 83% better than the national average of 41. Air quality has improved by 10 AQI points over the past decade. The area rarely experiences unhealthy air quality days. The primary pollutant of concern is Carbon Monoxide.
San Juan, Puerto Rico Air Quality: The Full Picture
San Juan, Puerto Rico (San Juan County) holds an AirHistory Air Quality Grade of A (excellent, scoring 92 out of 100), built from 7 years of EPA Air Quality System monitoring. Its median AQI fell 10 points between 2014 (17) and 2021 (7), and the five-year median now sits at 10 — inside the "Good" band on the EPA scale.
The pollutant driving most of the area's AQI readings is Carbon Monoxide. In 2021, it set the daily AQI on 41 of 41 monitored days (100% of the year), making it the controlling pollutant for the A grade. The single worst reading logged that year hit an AQI of 10 (Good), while the 90th-percentile day — the level the dirtiest 10% of days reach — came in at 9.
In 2021, San Juan County recorded 41 "Good" air days (100% of the 41 days with valid AQI data), 0 "Moderate" days, and 0 days at "Unhealthy for Sensitive Groups" or above. Over the most recent five years on record, monitors logged no days that crossed into "Unhealthy for Sensitive Groups" or worse.
The decade-long trend is improving: median AQI has been dropping by roughly 1.07 points per year. The cleanest year in the record was 2021 (median AQI 7), and the most polluted was 2014 (median AQI 17). Because the data come straight from federally certified EPA monitors, these figures track the Puerto Rico county the monitors physically sit in rather than a city boundary.
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10-Year AQI Trend
The solid line shows the median AQI each year. The dashed line shows the 90th percentile (worst 10% of days). This area has seen measurable air quality improvement over the decade.
Air Quality Day Breakdown
Number of days per year in each EPA AQI category. Green = Good (AQI 0-50), Yellow = Moderate (51-100), Orange = Unhealthy for Sensitive Groups (101-150), Red = Unhealthy or worse (151+).
Year-by-Year Data
| Year | Median AQI | 90th Pct | Max AQI | Good Days | Moderate | Unhealthy+ | Pollutant |
|---|---|---|---|---|---|---|---|
| 2021 | 7 | 9 | 10 | 41 | 0 | 0 | CO |
| 2020 | 9 | 32 | 39 | 216 | 0 | 0 | CO |
| 2019 | 14 | 17 | 35 | 277 | 0 | 0 | CO |
| 2017 | 8 | 17 | 35 | 246 | 0 | 0 | CO |
| 2016 | 15 | 19 | 83 | 327 | 1 | 0 | CO |
| 2015 | 13 | 23 | 66 | 321 | 8 | 0 | CO |
| 2014 | 17 | 23 | 31 | 358 | 0 | 0 | CO |
What This Means for San Juan County Residents
San Juan, Puerto Rico has received an Air Quality Grade of A (92/100) based on a decade of monitoring data from the EPA's air quality monitoring program. The current median AQI of 7 falls in the "Good" range.
Encouragingly, air quality here has been improving, with the median AQI dropping by 10 points over the monitoring period. This trend suggests continued investment in emission controls and cleaner energy.
The primary pollutant affecting this area is Carbon Monoxide. Over the past 5 years, this area has averaged 0 unhealthy air quality days per year, days when sensitive groups (children, elderly, those with respiratory conditions) should limit outdoor activity. The American Lung Association's State of the Air report provides additional context on long-term health risks from air pollution exposure.
Related Cities in Puerto Rico
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Frequently Asked Questions
San Juan, Puerto Rico has a current median AQI of 7, which falls in the "Good" range. The area has received an Air Quality Grade of A (92/100) based on 10 years of EPA monitoring data.
Air quality in San Juan, Puerto Rico is improving over the past decade. The median AQI has changed by -10 points from 2014 to 2021.
San Juan, Puerto Rico averages 0 unhealthy air quality days per year over the past 5 years. On these days, sensitive groups including children, the elderly, and those with respiratory conditions should limit outdoor activity.
The primary pollutant affecting San Juan, Puerto Rico is Carbon Monoxide. This is the dominant contributor to elevated AQI readings in the San Juan County area.
San Juan, Puerto Rico averages 0 unhealthy air days per year. This is relatively low, making it a reasonable choice for asthma sufferers. The primary pollutant is Carbon Monoxide, which can affect respiratory health.
With a median AQI of 7 (Good), outdoor exercise in San Juan, Puerto Rico is generally safe year-round. San Juan, Puerto Rico averages 0 days per year when athletes should move workouts indoors.