Mayagnez, Puerto Rico air quality history

Daily Air Quality Index summaries from EPA monitors in Mayagnez, Puerto Rico, 1999–2025.

98%

Good days in 2025

Median daily AQI, 2025

Days above 100 in 2025

227

Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Mayagnez, Puerto Rico on 227 days. 222 of those days (98%) were in the Good range, and the median daily AQI was 9. That median is about the same as the typical monitored county in Puerto Rico (median 9 across 5 counties), and lower than the typical monitored U.S. county (40). The main pollutant was ozone on 227 days. Across the years with fuller monitoring, the share of Good days rose: an average of 73% in 2019–2021 versus 96% in 2023–2025.

EPA did not report an AQI for every day of 2025 here (227 of 365 days). Figures describe monitored days only; seasonal monitoring (for example, ozone measured only in warmer months) can make a county look cleaner or dirtier than a full-year record would.

Years with fewer than 120 monitored days (2006, 2007, 2011, 2012, 2013, 2014…) are shown in the table but left out of comparisons and trend statements.

How the days broke down each year

Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.

Good
Moderate
Unhealthy for Sensitive Groups
Unhealthy
Very Unhealthy
Hazardous

Typical and high-end AQI over time

The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.

Median daily AQI
90th-percentile daily AQI

Main pollutant by day, 2025

On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.

Pollutant	Days as main pollutant	Share of monitored days
Ozone	227	100%

Year-by-year data

Annual AQI summary by year
Year	Days with AQI	Good	Moderate	Unhealthy for Sensitive Groups	Unhealthy	Very Unhealthy	Hazardous	Median AQI	90th pct.	Max AQI	Main pollutant
2025	227	222	1	2	0	1	1	9	21	350	Ozone
2024	341	341	0	0	0	0	0	11	26	39	Ozone
2023	285	254	31	0	0	0	0	25	51	64	PM2.5
2022	321	235	81	4	1	0	0	38	59	155	PM2.5
2021	334	231	101	2	0	0	0	38	62	142	PM2.5
2020	319	266	49	1	1	1	1	22	57	396	PM2.5
2019	202	136	66	0	0	0	0	33	63	87	PM2.5
2014	9	8	1	0	0	0	0	23	53	53	PM2.5
2013	81	75	6	0	0	0	0	26	48	60	PM2.5
2012	115	93	22	0	0	0	0	27	57	76	PM2.5
2011	67	60	7	0	0	0	0	27	51	61	PM2.5
2007	25	20	5	0	0	0	0	34	59	63	PM2.5
2006	100	74	26	0	0	0	0	35	58	72	PM2.5
2005	106	72	34	0	0	0	0	32	61	85	PM2.5
2004	100	82	18	0	0	0	0	33	54	65	PM2.5
2003	99	72	27	0	0	0	0	39	57	75	PM2.5
2002	96	72	24	0	0	0	0	39	56	68	PM2.5
2001	101	69	32	0	0	0	0	43	58	72	PM2.5
2000	99	77	22	0	0	0	0	41	55	69	PM2.5
1999	84	44	40	0	0	0	0	48	63	75	PM2.5

What this data can and can’t tell you

It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.

It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.

Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.

Counties in Puerto Rico with a similar median AQI in 2025

All monitored counties in Puerto Rico

Source: U.S. EPA AirData, “Annual AQI by County” files for 1999–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem