Bad Air Days in Benton County, Oregon: 2 a Year

2 bad air days a year

About the middle of monitored US counties. Ranked 440 of 996 monitored counties, where 1 is worst.

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

The bad-air season here

Most bad days here fall in September and August. 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 worst days on file

In 2000 to 2009 this county averaged under 1 bad days a year; in 2016 to 2025, 2. Not much has changed. The worst recent year was 2020, with 11 bad days on 366 monitored days.

Date	AQI	Main pollutant
2020-09-09	541	PM2.5
2020-09-12	431	PM2.5
2020-09-13	393	PM2.5
2020-09-14	275	PM2.5
2020-09-10	273	PM2.5

The air on a normal day

Across 2,215 monitored days from 2016 to 2022, the air in Benton County rated Good on 87% of them, more often than the 72% typical of monitored counties, and Moderate on 12%. The median day sat at AQI 22; one day in ten went above 53.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)100%2,215 days

Every recent year on file

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2022	206	183	23	0	0	21	68
2021	365	345	20	0	0	22	69
2020	366	313	42	11	11	23	541
2019	365	302	63	0	0	22	87
2018	362	313	47	2	0	22	119
2017	357	294	61	2	0	20	138
2016	194	175	19	0	0	20	68
2015	365	314	49	2	1	22	154
2014	364	318	45	1	0	21	115
2013	355	282	72	1	0	22	109
2012	355	306	49	0	0	21	69
2011	361	290	71	0	0	21	86
2010	364	331	33	0	0	20	72

Elsewhere in Oregon

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.