Caguas, Puerto Rico Air Quality Today
AirHistory tracks long-run EPA monitoring rather than live readings, so for the live number check AirNow.gov below. As a baseline, Caguas, Puerto Rico's most recent EPA year (2023) posted a median AQI of 6 (Good) against a 5-year median of 10 and an overall Grade of A. The dominant pollutant is Nitrogen Dioxide, which tells you which days are most likely to spike.
Check Today's Live AQI in Caguas, Puerto Rico
AirHistory is built on 10 years of EPA Air Quality System records, so it shows you what air quality in Caguas, Puerto Rico typically looks like — not the live reading for this exact hour. For today's real-time AQI, check AirNow.gov (the EPA's official live index) or the AirNow Fire and Smoke Map during wildfire season.
That said, the history is the best predictor of a normal day. In 2023, Caguas, Puerto Rico posted a median AQI of 6 (Good), with 242 "Good" days and 1 days that crossed into "Unhealthy for Sensitive Groups" or worse. The dominant pollutant, Nitrogen Dioxide, is the one most likely to push today's number up — Nitrogen dioxide is emitted directly from vehicle engines, power plants, and gas appliances. It is highest near busy roads and in urban centers. Long-term NO2 exposure is linked to the development of asthma in children and to higher rates of respiratory infection.
Caguas, Puerto Rico Air Quality Snapshot
| Air Quality Grade | A97/100 |
| 5-Year Median AQI | 10 (Good) |
| Most Recent Median AQI (2023) | 6 (Good) |
| Dominant Pollutant | Nitrogen Dioxide |
| 10-Year Trend | Improving (-2.30 AQI/yr) |
| Unhealthy Days (last 5 yr) | 5 |
| National Rank (cleanest = #1) | #9 of 1,020 (1th cleanest percentile) |
| Puerto Rico Rank | #2 of 11 |
What Does the A Grade Mean?
Caguas, 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.
Caguas, 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, Caguas, 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: San Juan, 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 Caguas, Puerto Rico's Air?
The dominant pollutant in Caguas, Puerto Rico is Nitrogen Dioxide. Nitrogen dioxide is emitted directly from vehicle engines, power plants, and gas appliances. It is highest near busy roads and in urban centers. Long-term NO2 exposure is linked to the development of asthma in children and to higher rates of respiratory infection.
Days by Dominant Pollutant (2023)
| Pollutant | Days as Dominant | Share of Year |
|---|---|---|
| Carbon Monoxide | 134 | 52% |
| Fine Particulate Matter (PM2.5) | 89 | 35% |
| Nitrogen Dioxide | 33 | 13% |
Is the Air Getting Better or Worse?
Air quality in Caguas, Puerto Rico has been improving over the past decade, with median AQI dropping by roughly 2.3 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 2016, Caguas, Puerto Rico posted a median AQI of 25. By 2023 that figure was 6 — a drop of 19 AQI points cleaner across 8 years of EPA records.
Year-by-Year AQI in Caguas, Puerto Rico
| Year | Median AQI | Good Days | Unhealthy Days | Dominant Pollutant |
|---|---|---|---|---|
| 2016 | 25 | 9 | 1 | NO2 |
| 2017 | 24 | 209 | 1 | NO2 |
| 2018 | 9 | 199 | 0 | CO |
| 2019 | 10 | 322 | 4 | NO2 |
| 2020 | 10 | 306 | 0 | CO |
| 2021 | 14 | 180 | 0 | CO |
| 2022 | 9 | 291 | 0 | NO2 |
| 2023 | 6 | 242 | 1 | CO |
Health Context for Caguas, Puerto Rico
Across the past five years, this area has logged just 5 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. NO2 concentrations drop quickly as you move away from traffic. Walking or biking on residential streets rather than along major arterials can cut personal exposure in half.
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.
More about Caguas, Puerto Rico
Caguas, Puerto Rico has an Air Quality Grade of A (excellent) with a 5-year median AQI of 10. The dominant pollutant is Nitrogen Dioxide, and air quality has been improving over the past decade.
This answer pulls from the EPA Air Quality System (AQS), the authoritative federal source for U.S. air quality and pollution monitoring. The headline number above is the direct answer; what follows is the additional context most readers need to use the answer for a real decision rather than just a fact lookup.
A practical caveat: the headline answer above reflects the most recent the EPA Air Quality System (AQS) vintage; underlying data is often revised for months after first publication, and the right reference for any specific decision is whichever vintage is current at the time of the decision. The as-of date is stamped on every page.
Source: EPA Outdoor Air Quality Data, 2026.