Bad Air Days in Pinal County, Arizona: 53 a Year

53 bad air days a year

Among the worst tenth of monitored US counties. Ranked 8 of 996 monitored counties, where 1 is worst.

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

Which months to watch

Most bad days here fall in June and July and August and October. Averaged over 2016 to 2025.

Is a purifier worth it here?

Particles (wildfire smoke, dust) cause enough bad days here to matter. A HEPA purifier sized to your bedroom removes them; run it with windows shut on bad days.
Upgrade the furnace or AC filter to MERV 13 so the whole house is filtered, not just one room.
With this many bad days, whole-home filtration is worth an HVAC contractor quote.
Ozone drives many bad days here. Purifiers and filters do not remove ozone, so do not buy one for that. Ozone peaks on hot afternoons: exercise outside in the morning.
Sign up for EnviroFlash ozone alerts for this area during the worst months.

The record for Pinal

In 2000 to 2009 this county averaged 99 bad days a year; in 2016 to 2025, 53. The air has improved. The worst recent year was 2020, with 84 bad days on 366 monitored days.

Date	AQI	Main pollutant
2016-07-29	1348	PM10
2025-01-08	1215	PM10
2020-08-16	1194	PM10
2018-04-12	1051	PM10
2019-06-08	929	PM10

An ordinary day in Pinal

Across 3,653 monitored days from 2016 to 2025, the air in Pinal County rated Good on 21% of them, less often than the 72% typical of monitored counties, and Moderate on 64%. The median day sat at AQI 69; one day in ten went above 108.

The pollutant setting the AQI on an ordinary day here:

coarse dust (PM10)49%1,805 days
ozone36%1,315 days
fine particles (PM2.5)15%533 days

Year by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	365	62	269	34	8	67	1215
2024	366	77	219	70	5	77	337
2023	365	109	211	45	7	64	709
2022	365	91	238	36	8	61	689
2021	365	72	240	53	4	70	198
2020	366	86	196	84	10	73	1194
2019	365	104	228	33	12	63	929
2018	365	71	243	51	17	67	1051
2017	365	55	242	68	9	75	358
2016	366	57	256	53	7	69	1348
2015	365	86	233	46	13	63	924
2014	365	51	227	87	32	72	924
2013	365	91	195	79	23	69	947
2012	366	46	237	83	14	75	605
2011	365	65	185	115	39	83	2403
2010	365	88	236	41	2	69	1786

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

Elsewhere in Arizona

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.