Bad Air Days in Washington County, Kentucky: under 1 a Year

under 1 bad air days a year

Rare: among the cleanest-air counties EPA monitors. Ranked 896 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. 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 record for Washington

In 2000 to 2009 this county averaged 15 bad days a year; in 2016 to 2025, under 1. The air has improved. The worst recent year was 2023, with 2 bad days on 358 monitored days.

Date	AQI	Main pollutant
2017-07-19	112	Ozone
2023-06-09	108	Ozone
2023-06-06	105	Ozone
2025-09-19	97	Ozone
2023-06-02	93	Ozone

Most days, not the worst ones

Across 3,601 monitored days from 2016 to 2025, the air in Washington County rated Good on 92% of them, more often than the 72% typical of monitored counties, and Moderate on 8%. The median day sat at AQI 37; one day in ten went above 49.

The pollutant setting the AQI on an ordinary day here:

ozone100%3,601 days

Year by year

Year	Days monitored	Good	Moderate	Over 100	Median AQI	Highest AQI
2025*	360	325	35	0	38	97
2024	349	315	34	0	39	74
2023	358	315	41	2	40	108
2022	364	340	24	0	37	77
2021	362	342	20	0	36	87
2020	364	352	12	0	34	77
2019	364	331	33	0	39	80
2018	359	326	33	0	35	77
2017	362	332	29	1	38	112
2016	359	326	33	0	38	90
2015	360	333	26	1	37	101
2014	362	314	47	1	37	101
2013	362	334	28	0	38	93
2012	364	280	72	12	42	150
2011	339	272	64	3	40	112
2010	361	271	85	5	41	126

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

Elsewhere in Kentucky

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.