Metro area air quality · 2025

Mayaguez, PR

Median AQI 9 (Good). 97.8% of monitored days rated Good across this metro's EPA monitoring network.

9
Median AQI
97.8%
Good-air days
2
Unhealthy days
98%
Cleaner than US metros

Mayaguez, PR posted a 2025 median AQI of 9 (Good) with 97.8% Good days

According to the U.S. EPA Air Quality System, the Mayaguez, PR CBSA recorded a median AQI of 9 across 227 monitored days in 2025, with 97.8% rated Good and 2 unhealthy or worse. This is an annual metro comparison, not a live advisory.

Data source EPA Air Quality System (AQS)

Cleaner than US metros
The Mayaguez, PR CBSA's 97.8% Good-day share places it cleaner than 98% of US metros in 2025.
Closest median-AQI peer
Evanston, WY (100.0% Good, median AQI 9) is the closest nationwide median-AQI peer to Mayaguez, PR.
2020–2025 Good-day shift
Mayaguez, PR's Good-day share moved +15.4 points from 2020 to 2025 (median AQI -13).
Median AQI
Median AQI: 9

Aggregated from EPA Air Quality System (2025), 227 monitored days. EPA AQS →

The verdict

Mayaguez, PR sits in the upper Good-day tercile among EPA CBSA metros on this site (97.8% of 227 monitored days). On the EPA scale the metro runs good, among the cleanest 10% of US metros, with a median AQI of 9 and 97.8% of 227 monitored days in the Good band.

9
median AQI · Good
97.8%
days rated Good
98%
cleaner than US metros
350
worst single reading

2 days reached Unhealthy or worse across the metro's monitors in 2025.

Annual release change

What changed in the 2025 EPA annual release

2024 → 2025
  • Mayaguez, PR metro's peak single-day AQI rose from 39 to 350 between the 2024 and 2025 EPA annual releases, a change of +311 points.

Compared against 341 monitored days in 2024 and 223 in 2025. These are arithmetic differences between two stored EPA annual summaries, not a cause claim or a live advisory.

National release changes Two-year CSV

Mayaguez, PR sits in the upper Good-day tercile among EPA CBSA metros on this site (97.8% of 227 monitored days). Signature read: 97.8% Good-day share (high tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 9 over 227 measured days in 2025 (Good / Excellent). The monitored-day split lands at 222 Good (98%), 1 Moderate (0%), and 2 Unhealthy-for-Sensitive-Groups (1%). The 90th-percentile AQI finished at 21; the highest single-day reading hit 350 (Hazardous).

Across 2020–2025, Good-day share shifted +15.4 points and median AQI moved -13 (improving). The annual record contains 2 days at Unhealthy or worse. Metros with comparable AQI profiles include Evanston, WY (100.0% good, AQI 9); Santa Rosa, CA (100.0% good, AQI 9); Bozeman, MT (98.1% good, AQI 11).

Health effects of air pollution →

Air Quality Summary

Median AQI

9

Good

Good Days

97.8%

222 of 227 days

Max AQI

350

Hazardous

Health Grade

Excellent

90th pct: 21

AQI Day Breakdown (2025)

Distribution of 227 monitored days across EPA AQI categories.

Good

222

98%

Moderate

1

0%

USG

2

1%

Unhealthy

0

0%

Very Unhealthy

1

0%

Hazardous

1

0%

Health Impact Assessment

Excellent

The Mayaguez, PR metro area's air quality is rated Excellent based on 97.8% good air days. There were 2 unhealthy days in 2025 when outdoor activity should be limited.

Air quality posed significant health risk in 2025. Sensitive groups, including people with asthma, COPD, cardiovascular conditions, children, pregnant women, and adults over 65, should monitor AirNow.gov alerts and limit outdoor activity on Unhealthy (AQI 151+) and Very Unhealthy (201+) days. Peak readings reached AQI 350, well into the Hazardous range.

Sensitive group advisory

People with asthma, COPD, heart disease, children, pregnant women, and adults 65+ should follow EPA AQI alerts daily and limit outdoor exertion when AQI exceeds 100. Real-time conditions: airnow.gov.

How does the Mayaguez, PR metro compare?

How Mayaguez, PR compares

Good-day share better than typical
Mayaguez, PR 97.8%
Evanston, WY 100.0%
Typical US metro 70.6%
Median AQI better than typical
Mayaguez, PR 9
Evanston, WY 9
Typical US metro 41
Unhealthy days / yr worse than typical
Mayaguez, PR 2
Evanston, WY 0
Typical US metro 1

5-Year Air Quality Trend

Air quality is improving in the Mayaguez, PR metro. Highest Good-day share: 2024 (100.0%, 341 of 341 monitored days).

Year Good Moderate Unhealthy Median AQI
2020 266 49 1 22
2021 231 101 0 38
2022 235 81 1 38
2023 254 31 0 25
2024 341 0 0 11
2025 222 1 0 9

Metros with a similar median AQI

CBSA peers nationwide whose annual median AQI sits near Mayaguez, PR (9).

Evanston, WY

Median AQI 9 · 100.0% Good-day share

9

Santa Rosa, CA

Median AQI 9 · 100.0% Good-day share

9

Bozeman, MT

Median AQI 11 · 98.1% Good-day share

11

Show Low, AZ

Median AQI 13 · 99.5% Good-day share

13

Havre, MT

Median AQI 14 · 92.1% Good-day share

14

Ponce, PR

Median AQI 3 · 91.4% Good-day share

3

Metros with similar unhealthy-day exposure

A second relationship type: metros whose unhealthy-or-worse day count is closest to Mayaguez, PR's 2 (independent of median AQI).

Ardmore, OK

2 unhealthy-or-worse days · median AQI 45

45

Bridgeport-Stamford-Norwalk, CT

2 unhealthy-or-worse days · median AQI 44

44

Chattanooga, TN-GA

2 unhealthy-or-worse days · median AQI 49

49

Cincinnati, OH-KY-IN

2 unhealthy-or-worse days · median AQI 56

56

Columbus, GA-AL

2 unhealthy-or-worse days · median AQI 48

48

Davenport-Moline-Rock Island, IA-IL

2 unhealthy-or-worse days · median AQI 46

46

Frequently Asked Questions

How many unhealthy air days does Mayaguez, PR have? ▼
In 2025, the Mayaguez, PR metro area recorded 2 unhealthy air days (0 Unhealthy, 1 Very Unhealthy, 1 Hazardous). The maximum AQI reached 350.
What is the air quality in the Mayaguez, PR metro area? ▼
The Mayaguez, PR metro area has a median Air Quality Index (AQI) of 9, rated "Good." 97.8% of monitored days (222 out of 227) had good air quality in 2025.
Is air quality in Mayaguez, PR getting better or worse? ▼
Air quality in the Mayaguez, PR metro is improving across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2024 at 100.0% (341 of 341 days). Lowest qualifying Good-day share: 2021 at 69.6% (231 of 332 days).
What does AQI 9 mean for health? ▼
An AQI of 9 is "Good", air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.
How does Mayaguez, PR compare to other metro areas? ▼
The Mayaguez, PR metro has 97.8% good air days. Similar metros: Evanston, WY (100.0% good), Santa Rosa, CA (100.0% good), Bozeman, MT (98.1% good).
What is the 90th percentile AQI for Mayaguez, PR? ▼
The 90th percentile AQI for the Mayaguez, PR metro area is 21, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 350 (Hazardous).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Mayaguez, PR, 2025. See our methodology for how AQI, median, and coverage figures are computed.

Read our methodology , how this data is sourced, computed, and verified.

Source: U.S. EPA Air Quality System (AQS) Annual AQI by CBSA summary, Mayaguez, PR · 2020–2025