Bad Air Days in Bay County, Michigan: under 1 a Year

under 1 bad air day a year

Fewer bad air days than most monitored US counties. Ranked 700 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly particles: smoke and dust (100% particle days).

Which months to watch

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

What actually helps 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

The worst recent year was 2023, with 6 bad days on 363 monitored days.

Date	AQI	Main pollutant
2023-06-27	192	PM2.5
2023-06-29	176	PM2.5
2023-06-28	156	PM2.5
2025-08-03	139	PM2.5
2025-08-04	139	PM2.5

Most days, not the worst ones

Across 3,555 monitored days from 2016 to 2025, the air in Bay County rated Good on 77% of them, more often than the 72% typical of monitored counties, and Moderate on 23%. The median day sat at AQI 34; one day in ten went above 56.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)100%3,555 days

Bay County by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	358	252	103	3	0	39	139
2024	363	277	86	0	0	37	73
2023	363	229	128	6	3	42	192
2022	354	287	67	0	0	32	85
2021	363	290	73	0	0	28	86
2020	365	325	40	0	0	22	77
2019	316	252	64	0	0	34	85
2018	356	266	90	0	0	37	85
2017	362	279	83	0	0	36	82
2016	355	264	91	0	0	37	83
2015	361	220	141	0	0	44	82
2014	348	205	143	0	0	45	96
2013	114	74	40	0	0	38	71
2012	119	83	36	0	0	36	87
2011	118	79	39	0	0	32	79
2010	121	86	34	1	0	33	103

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

Michigan compared

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.