Bad Air Days in Bremer County, Iowa: 2 a Year

2 bad air days a year

Fewer bad air days than most monitored US counties. Ranked 508 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 May. Averaged over 2016 to 2025.

What to buy, and what not to

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 record for Bremer

In 2000 to 2009 this county averaged 4 bad days a year; in 2016 to 2025, 2. The air has improved. The worst recent year was 2023, with 10 bad days on 235 monitored days.

Date	AQI	Main pollutant
2023-06-20	151	Ozone
2023-06-05	136	Ozone
2023-06-22	133	Ozone
2023-06-03	129	Ozone
2023-06-23	126	Ozone

Most days, not the worst ones

Across 2,383 monitored days from 2016 to 2025, the air in Bremer County rated Good on 91% of them, more often than the 72% typical of monitored counties, and Moderate on 9%. The median day sat at AQI 38; one day in ten went above 52.

The pollutant setting the AQI on an ordinary day here:

ozone100%2,383 days

Every recent year on file

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	241	210	30	1	0	38	115
2024	234	207	27	0	0	40	74
2023	235	180	45	10	1	42	151
2022	243	235	8	0	0	37	67
2021	244	223	21	0	0	40	90
2020	244	232	12	0	0	35	87
2019	243	228	15	0	0	37	90
2018	245	224	19	2	0	37	112
2017	241	224	17	0	0	36	93
2016	213	196	17	0	0	33	80
2015	214	200	14	0	0	36	80
2014	212	195	17	0	0	37	87
2013	210	197	13	0	0	38	77
2012	213	158	53	2	0	43	105
2011	213	191	22	0	0	40	97
2010	214	187	26	1	0	38	108

*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.