Bad Air Days in Ponce, Puerto Rico: 2 a Year

2 bad air days a year

Fewer bad air days than most monitored US counties. Ranked 528 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly particles: smoke and dust (75% particle days).

The bad-air season here

Most bad days here fall in January and February and September. Averaged over 2016 to 2025.

What to buy, and what not to

Bad air days are rare here. A standard furnace filter is enough; no purifier needed for outdoor air.
On the odd bad day, check AirNow and keep windows shut.

The worst days on file

The worst recent year was 2021, with 4 bad days on 217 monitored days.

Date	AQI	Main pollutant
2021-02-02	380	CO
2021-02-01	277	CO
2017-05-19	259	PM2.5
2021-02-03	228	CO
2021-02-04	156	CO

An ordinary day in Ponce

Across 3,126 monitored days from 2016 to 2025, the air in Ponce rated Good on 78% of them, more often than the 72% typical of monitored counties, and Moderate on 21%. The median day sat at AQI 27; one day in ten went above 55.

The pollutant setting the AQI on an ordinary day here:

coarse dust (PM10)40%1,242 days
fine particles (PM2.5)39%1,226 days
carbon monoxide21%658 days

Every recent year on file

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	257	235	22	0	0	3	74
2024	336	317	19	0	0	3	82
2023	340	258	82	0	0	30	83
2022	295	264	31	0	0	18	99
2021	217	176	37	4	4	30	380
2020	360	319	41	0	0	23	81
2019	351	204	141	6	0	43	136
2018	357	146	206	5	0	55	118
2017	249	194	54	1	1	31	259
2016	364	331	33	0	0	25	73
2015	365	328	37	0	0	24	69
2014	350	314	36	0	0	20	68
2013	363	335	28	0	0	28	61
2012	357	324	33	0	0	22	75
2011	175	160	15	0	0	27	63
2010	122	107	15	0	0	26	91

*2025 may be a partial year in EPA's file.

Puerto Rico compared

Catano11/yr
Juncos5/yr
Bayamon3/yr
Mayagnez3/yr
Guaynabo2/yr
Caguas1/yr
Fajardothin data
Adjuntasthin data

How this is counted

A bad air day is a day the county's daily AQI from EPA AirData went above 100, the level where EPA tells children, older adults and people with asthma or heart disease to cut back outdoors. Monitors do not run every day, so yearly counts are scaled to 365 days. This is the record, not today's air: for that, check AirNow. More on the method in how the county numbers are made, on the AQI 100 line in what counts as a bad air day.