Median AQI
3
Good
Puerto Rico · County air quality · 2025
Caguas County, Puerto Rico
Median AQI 3 (Good). 94.3% of monitored days rated Good, direct from EPA Air Quality System stations.
- 3
- Median AQI
- 94.3%
- Good-air days
- 0
- Unhealthy days
- 86%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Caguas County's air is good on balance, cleaner than most US counties, a median AQI of 3 with 94.3% of 157 monitored days in the Good band, driven mainly by CO.
- 3
- median AQI · Good
- 94.3%
- days rated Good
- CO
- main pollutant
- 86%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 63.
Data updated July 2026
- Good · 148 d · 94.3%
- Moderate · 9 d · 5.7%
How did Caguas County's air break down in 2025?
Across 157 monitored days, 148 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 63 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 157 days monitored. Median AQI: 3 (Good).
Insights: Caguas County, Puerto Rico. EPA monitors recorded a median Air Quality Index of 3 across 157 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 148 (94%) fell in the Good band (AQI 0–50), 9 (6%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 29, while the worst single-day peak hit 63 (Moderate). Residents averaged about 28.3 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as CO (100 days), PM2.5 (57 days). Across the 2020–2025 trend window, good days shifted by -158 and the median AQI moved -7 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 63, moderate but never Unhealthy. Nearby counties show comparable readings: Bayamon (88.5% good, AQI 29); Catano (64.6% good, AQI 44); Fajardo (85.7% good, AQI 29); Guayama (100.0% good, AQI 18); Guaynabo (86.0% good, AQI 30); Mayagnez (96.9% good, AQI 12).
Air Quality Summary
Good Days
94.3%
148 of 157 monitored days
19.3pp vs 75% target
Max AQI Recorded
63
Moderate
Health Grade
Excellent
90th-pct AQI 29
Caguas County, Good days share 94.3%
National avg
Share of monitored days at AQI 0-50 (Good band).
Caguas County, Unhealthy-or-worse share 0.0%
National avg
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
AQI Day Breakdown (2025)
Distribution of 157 monitored days across EPA AQI categories.
Good
148
94%
Moderate
9
6%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Caguas County.
- CO · 100 days · 63.7%
- PM2.5 · 57 days · 36.3%
Health Impact Assessment
Excellent
Caguas County's air quality is rated Excellent based on 94.3% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 94.3% of monitored days in 2025, with a median AQI of 3. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is CO, driving AQI on 100 of 157 monitored days.
5-Year Air Quality Trend
Air quality is improving in Caguas County. Best year: 2024 (343 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 306 | 12 | 0 | 0 | 10 | 72 |
| 2021 | 180 | 17 | 0 | 0 | 14 | 75 |
| 2022 | 291 | 16 | 0 | 0 | 9 | 76 |
| 2023 | 242 | 13 | 1 | 0 | 6 | 105 |
| 2024 | 343 | 13 | 0 | 1 | 3 | 174 |
| 2025 | 148 | 9 | 0 | 0 | 3 | 63 |
How does Caguas County compare?
How Caguas County compares
Good-day share better than US avg
Caguas County 94.3%
Bayamon County, Puerto Rico 88.5%
US average 76.5%
Median AQI better than US avg
Caguas County 3
Bayamon County, Puerto Rico 29
US average 38
Unhealthy days / yr about average
Caguas County 0
Bayamon County, Puerto Rico 0
US average 0
Other Counties in Puerto Rico
Air quality comparison for nearby counties in Puerto Rico.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Caguas County.
Custer County, Idaho
AQI 3 · 100.0% good
Jackson County, Colorado
AQI 3 · 100.0% good
Garfield County, Utah
AQI 4 · 100.0% good
Karnes County, Texas
AQI 4 · 100.0% good
Lake County, Montana
AQI 4 · 100.0% good
Rosebud County, Montana
AQI 4 · 100.0% good
What Caguas County's air means for you
The air here stays in the breathable range year-round, with CO the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-CO days, the guide explains what a median of 3 means for exposure. Health guidance
- See how Caguas County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Caguas County with its Puerto Rico neighbours before drawing a conclusion about the region. All of Puerto Rico
Based on 157 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
More Air Quality Data
Air Quality Guides
Frequently Asked Questions
What is the air quality in Caguas County, Puerto Rico? ▼
Caguas County has a median Air Quality Index (AQI) of 3, rated "Good." 94.3% of monitored days (148 out of 157) had good air quality in 2025.
What is the main pollutant in Caguas County? ▼
The primary pollutant in Caguas County is Carbon Monoxide (CO), which was the main AQI driver on 100 days (64% of monitored days). Reduces oxygen delivery to organs. Dangerous at high levels.
How many unhealthy air days does Caguas County have? ▼
In 2025, Caguas County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 63.
Is the air quality in Caguas County getting better or worse? ▼
Air quality in Caguas County is improving based on 5-year trends (2020-2025). Best year: 2024 with 343 good days. Worst year: 2025 with 148 good days.
What does AQI 3 mean for health? ▼
Caguas County's median AQI of 3 falls in the "Good" category. See the <a href="/guides/understanding-aqi" class="underline">AQI category guide</a> for what each range means for health.
How does Caguas County compare to other counties in Puerto Rico? ▼
Caguas County has 94.3% good air days. Nearby counties in Puerto Rico: Bayamon (88.5% good), Catano (64.6% good), Fajardo (85.7% good), Guayama (100.0% good), Guaynabo (86.0% good), Mayagnez (96.9% good).
What is the 90th percentile AQI in Caguas County? ▼
The 90th percentile AQI for Caguas County is 29, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 63 (Moderate).
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025 (aqs.epa.gov). For current conditions (not shown here — this page is historical annual data), see EPA AirNow (airnow.gov). See our methodology for how AQI, median, and coverage figures are computed.
Informational only, not professional advice. Data from EPA AQS. See our disclaimer.
Every figure on PlainAir is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.