Adjuntas, Puerto Rico air quality history

Daily Air Quality Index summaries from EPA monitors in Adjuntas, Puerto Rico, 2005–2021.

100%

Good days in 2021

Median daily AQI, 2021

Days above 100 in 2021

Days with an AQI in 2021 (of 365)

In 2021, EPA reported a daily Air Quality Index (AQI) for Adjuntas, Puerto Rico on 7 days. 7 of those days (100%) were in the Good range, and the median daily AQI was 14. That median is lower than the typical monitored county in Puerto Rico (median 30 across 5 counties), and lower than the typical monitored U.S. county (41). The main pollutant was fine particles (PM2.5) on 7 days.

EPA did not report an AQI for every day of 2021 here (7 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.

The most recent year with data for this county is 2021; EPA's files for 2022–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (2016, 2017, 2018, 2019, 2020, 2021…) 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, 2021

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
Fine particles (PM2.5)	7	100%

Year-by-year data

Annual AQI summary by year
Year	Days with AQI	Good	Moderate	Median AQI	90th pct.	Max AQI	Main pollutant
2021	7	7	0	14	23	23	PM2.5
2020	57	52	5	18	50	63	PM2.5
2019	117	98	19	24	54	70	PM2.5
2018	27	27	0	19	30	42	PM2.5
2017	47	35	12	37	60	90	PM2.5
2016	97	85	12	28	55	75	PM2.5
2015	91	80	11	27	52	64	PM2.5
2014	42	36	6	24	52	61	PM2.5
2013	93	85	8	22	48	59	PM2.5
2012	77	72	5	24	48	70	PM2.5
2011	14	13	1	14	21	58	PM2.5
2009	44	41	3	21	37	54	PM2.5
2008	112	110	2	24	41	77	PM2.5
2007	92	70	22	33	55	71	PM2.5
2006	103	80	23	34	55	78	PM2.5
2005	107	91	16	27	56	69	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.

All monitored counties in Puerto Rico

Source: U.S. EPA AirData, “Annual AQI by County” files for 2005–2021 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem