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.

Compiled by PlainAirData · August 23, 2026

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

The Mayaguez, PR metro runs good on the EPA scale, among the cleanest 10% of US metros, a median AQI of 9 with 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.

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.

Insights: Mayaguez, PR metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 9 over 227 measured days in 2025, which corresponds to a Good band and a Excellent metro-wide health grade. The monitored-day split lands at 222 Good days (98%), 1 Moderate (0%), and 2 Unhealthy-for-Sensitive-Groups (1%). The 90th-percentile AQI finished at 21 while the highest single-day reading hit 350 (Hazardous). Metro residents averaged roughly 29.3 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, the share of monitored days rated Good shifted by +15.4 points (measured against 316 monitored days in 2020 and 223 in 2025, so raw day counts are not comparable) and the median AQI moved -13 points, which classifies the multi-year trajectory as improving. The annual record contains 2 days at Unhealthy or worse. On those days, the EPA recommends that sensitive groups limit prolonged outdoor exertion. 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).

Air Quality Summary

Median AQI

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

USG

Unhealthy

Very Unhealthy

Hazardous

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

Compare against

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	Max AQI
2020	266	49	1	22	396
2021	231	101	0	38	142
2022	235	81	1	38	155
2023	254	31	0	25	64
2024	341	0	0	11	39
2025	222	1	0	9	350

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

Santa Rosa, CA

Median AQI 9 · 100.0% Good-day share

Bozeman, MT

Median AQI 11 · 98.1% Good-day share

Show Low, AZ

Median AQI 13 · 99.5% Good-day share

Havre, MT

Median AQI 14 · 92.1% Good-day share

Ponce, PR

Median AQI 3 · 91.4% Good-day share

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

Bridgeport-Stamford-Norwalk, CT

2 unhealthy-or-worse days · median AQI 44

Chattanooga, TN-GA

2 unhealthy-or-worse days · median AQI 49

Cincinnati, OH-KY-IN

2 unhealthy-or-worse days · median AQI 56

Columbus, GA-AL

2 unhealthy-or-worse days · median AQI 48

Davenport-Moline-Rock Island, IA-IL

2 unhealthy-or-worse days · median AQI 46

More Air Quality Data

Explore EPA air quality rankings and guides across U.S. metros and counties.

Cleanest Metro Areas

U.S. metros ranked by their share of Good air-quality days.

Worst Air Quality

Counties and metros with the most unhealthy air days.

All Metro Areas

Annual AQI by CBSA for every monitored U.S. metro area.

Best and Worst City Air

What drives urban air quality and how metro areas compare.

Air Quality Guides

Frequently Asked Questions

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.

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.

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.

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).

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).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset, 2020–2025. 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 files (metro-level) · 2020–2025 Accessed 2026-07-06

Send the source-year summary or download its ready-to-use data card.

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Every figure on PlainAirData 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.