Bad Air Days in Lake County, Minnesota: 2 a Year

2 bad air days a year

About the middle of monitored US counties. Ranked 475 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly particles: smoke and dust (91% particle days).

When the bad days come in Lake

Most bad days here fall in July and August and June and May. 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 1 bad days a year; in 2016 to 2025, 2. Not much has changed. The worst recent year was 2025, with 15 bad days on 361 monitored days.

Date	AQI	Main pollutant
2025-07-12	191	PM2.5
2025-07-30	175	PM2.5
2025-07-31	172	PM2.5
2025-08-01	162	PM2.5
2021-08-26	160	PM2.5

Most days, not the worst ones

Across 3,635 monitored days from 2016 to 2025, the air in Lake County rated Good on 89% of them, more often than the 72% typical of monitored counties, and Moderate on 10%. The median day sat at AQI 31; one day in ten went above 51.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)49%1,790 days
ozone43%1,579 days
coarse dust (PM10)7%266 days

Every recent year on file

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	361	310	36	15	7	31	191
2024	366	330	35	1	0	32	110
2023	365	282	81	2	0	36	114
2022	357	342	15	0	0	31	78
2021	362	315	43	4	1	31	160
2020	365	344	21	0	0	34	71
2019	363	333	30	0	0	31	83
2018	365	310	55	0	0	34	96
2017	365	330	35	0	0	30	85
2016	366	347	19	0	0	24	86
2015	365	332	32	1	0	32	110
2014	365	310	55	0	0	31	93
2013	365	311	54	0	0	33	86
2012	365	300	64	1	0	33	108
2011	356	282	66	8	1	34	170
2010	350	299	50	1	0	30	123

*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.