What Is the Air Quality in Juncos, Puerto Rico?
Juncos, Puerto Rico has an Air Quality Grade of A (excellent) with a 5-year median AQI of 9. The dominant pollutant is Ground-Level Ozone, and air quality has been improving over the past decade.
Juncos, Puerto Rico Air Quality Snapshot
| Air Quality Grade | A91/100 |
| 5-Year Median AQI | 9 (Good) |
| Most Recent Median AQI (2020) | 9 (Good) |
| Dominant Pollutant | Ground-Level Ozone |
| 10-Year Trend | Improving (-1.94 AQI/yr) |
| Unhealthy Days (last 5 yr) | 6 |
| National Rank (cleanest = #1) | #7 of 1,020 (1th cleanest percentile) |
| Puerto Rico Rank | #1 of 11 |
What Does the A Grade Mean?
Juncos, Puerto Rico earns an A — it is among the cleanest U.S. cities tracked by EPA monitoring, with median AQI averaging just 9 over the past five years. Days in the "Good" category dominate the calendar; air-quality alerts are rare.
Juncos, Puerto Rico's 5-year median AQI of 9 is 32 points below the national average of 41 — meaningfully cleaner than the typical U.S. metro tracked here. Within Puerto Rico, Juncos, 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).
What's in Juncos, Puerto Rico's Air?
The dominant pollutant in Juncos, Puerto Rico is Ground-Level Ozone. Ground-level ozone forms when sunlight reacts with vehicle exhaust and industrial emissions. It is worst on hot, sunny, stagnant summer days. Ozone irritates the lungs, triggers asthma attacks, and reduces lung function — even healthy adults can feel chest tightness and shortness of breath after exercising in elevated ozone.
Days by Dominant Pollutant (2020)
| Pollutant | Days as Dominant | Share of Year |
|---|---|---|
| Ground-Level Ozone | 348 | 100% |
Is the Air Getting Better or Worse?
Air quality in Juncos, Puerto Rico has been improving over the past decade, with median AQI dropping by roughly 1.9 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, Juncos, Puerto Rico posted a median AQI of 20. By 2020 that figure was 9 — a drop of 11 AQI points cleaner across 5 years of EPA records.
Year-by-Year AQI in Juncos, Puerto Rico
| Year | Median AQI | Good Days | Unhealthy Days | Dominant Pollutant |
|---|---|---|---|---|
| 2014 | 20 | 344 | 0 | Ozone |
| 2015 | 19 | 312 | 0 | Ozone |
| 2016 | 5 | 295 | 6 | Ozone |
| 2017 | 5 | 194 | 0 | Ozone |
| 2020 | 9 | 338 | 6 | Ozone |
Health Context for Juncos, Puerto Rico
Across the past five years, this area has logged just 6 days where AQI rose into the "Unhealthy for Sensitive Groups" range or worse — about 1 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. Because ozone peaks in the afternoon on hot sunny days, plan outdoor exercise for early morning or after sunset on bad-air days.
How This Grade Is Calculated
The AirHistory Air Quality Grade combines four signals: the 5-year median AQI (40% of the score), the 10-year trend direction (30%), the count of unhealthy days per year (20%), and the dominant pollutant type (10%). All four come directly from the EPA Air Quality System (AQS), which aggregates readings from federally certified monitors. Read the full methodology.
Juncos, Puerto Rico has an Air Quality Grade of A (excellent) with a 5-year median AQI of 9. The dominant pollutant is Ground-Level Ozone, and air quality has been improving over the past decade.
The data source behind this answer is the EPA Air Quality System (AQS). Every figure on the page traces back to that source; the methodology page describes the inputs and the refresh cadence in full detail.
For readers turning this answer into action: cross-reference against the underlying the EPA Air Quality System (AQS) record before acting on time-sensitive decisions. The site renders the data as it was published; subsequent revisions can shift the picture, and the live federal data is always the authoritative current reference.
Source: EPA Outdoor Air Quality Data, 2026.