Bad Air Days in York County, Maine: 2 a Year

2 bad air days a year

Fewer bad air days than most monitored US counties. Ranked 498 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly ozone: summer smog (0% particle days).

When the bad days come in York

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

Is a purifier worth it here?

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

In 2000 to 2009 this county averaged 13 bad days a year; in 2016 to 2025, 2. The air has improved. The worst recent year was 2021, with 3 bad days on 240 monitored days.

Date	AQI	Main pollutant
2025-08-12	169	Ozone
2017-06-12	159	Ozone
2025-06-05	147	Ozone
2021-08-26	129	Ozone
2024-06-19	129	Ozone

Most days, not the worst ones

Across 2,693 monitored days from 2016 to 2025, the air in York County rated Good on 93% of them, more often than the 72% typical of monitored counties, and Moderate on 6%. The median day sat at AQI 37; one day in ten went above 48.

The pollutant setting the AQI on an ordinary day here:

ozone100%2,693 days

Every recent year on file

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	365	353	9	3	1	34	169
2024	361	346	14	1	0	34	129
2023	328	304	24	0	0	35	84
2022	246	230	14	2	0	38	126
2021	240	217	20	3	0	37	129
2020	235	223	12	0	0	39	87
2019	231	216	14	1	0	38	115
2018	227	207	18	2	0	40	119
2017	224	204	19	1	1	37	159
2016	236	211	23	2	0	38	108
2015	214	194	17	3	0	40	136
2014	214	193	19	2	0	39	101
2013	214	186	21	7	0	40	147
2012	214	183	26	5	0	41	140
2011	271	237	29	5	1	36	151
2010	352	306	40	6	1	36	174

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

Nearby counties on file

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, and on why a purifier does not touch ozone in smoke vs ozone.