Bad Air Days in Bullitt County, Kentucky: 2 a Year

2 bad air days a year

Fewer bad air days than most monitored US counties. Ranked 507 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.

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 record for Bullitt

In 2000 to 2009 this county averaged 16 bad days a year; in 2016 to 2025, 2. The air has improved. The worst recent year was 2023, with 6 bad days on 238 monitored days.

Date	AQI	Main pollutant
2018-07-13	150	Ozone
2021-07-28	143	Ozone
2018-06-14	126	Ozone
2023-06-06	126	Ozone
2016-09-14	122	Ozone

Most days, not the worst ones

Across 2,375 monitored days from 2016 to 2025, the air in Bullitt County rated Good on 87% of them, more often than the 72% typical of monitored counties, and Moderate on 13%. The median day sat at AQI 40; one day in ten went above 55.

The pollutant setting the AQI on an ordinary day here:

ozone100%2,375 days

Year by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	232	205	27	0	0	39	90
2024	244	201	42	1	0	43	105
2023	238	188	44	6	0	44	126
2022	239	212	26	1	0	40	101
2021	237	212	24	1	0	37	143
2020	240	224	15	1	0	37	115
2019	243	214	29	0	0	41	93
2018	233	196	35	2	0	38	150
2017	233	208	25	0	0	39	97
2016	236	202	33	1	0	39	122
2015	242	215	25	2	0	39	108
2014	222	194	27	1	0	38	112
2013	243	222	20	1	0	37	105
2012	245	183	56	6	1	43	151
2011	266	148	114	4	1	48	187
2010	284	119	157	8	0	54	119

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

Kentucky 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, and on why a purifier does not touch ozone in smoke vs ozone.