Bad Air Days in Ashtabula County, Ohio: 4 a Year

4 bad air days a year

About the middle of monitored US counties. Ranked 285 of 996 monitored counties, where 1 is worst.

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

Which months to watch

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

What to buy, and what not to

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.

The worst days on file

In 2000 to 2009 this county averaged 38 bad days a year; in 2016 to 2025, 4. The air has improved. The worst recent year was 2016, with 6 bad days on 213 monitored days.

Date	AQI	Main pollutant
2023-06-02	147	Ozone
2017-07-19	143	Ozone
2022-06-21	133	Ozone
2018-05-25	129	Ozone
2016-05-25	126	Ozone

Most days, not the worst ones

Across 2,405 monitored days from 2016 to 2025, the air in Ashtabula County rated Good on 86% of them, more often than the 72% typical of monitored counties, and Moderate on 13%. The median day sat at AQI 40; one day in ten went above 58.

The pollutant setting the AQI on an ordinary day here:

ozone100%2,405 days

Ashtabula County by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	245	199	43	3	0	43	122
2024	245	205	38	2	0	41	108
2023	245	208	35	2	0	42	147
2022	239	211	23	5	0	38	133
2021	243	213	28	2	0	38	112
2020	241	224	17	0	0	37	93
2019	245	221	23	1	0	39	112
2018	244	208	33	3	0	39	129
2017	245	212	31	2	0	39	143
2016	213	171	36	6	0	41	126
2015	210	168	39	3	0	41	143
2014	213	176	35	2	0	41	119
2013	213	178	33	2	0	39	108
2012	213	150	54	9	2	44	179
2011	211	153	50	8	1	42	154
2010	214	146	50	18	1	44	156

*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.