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

under 1 bad air day a year

Fewer bad air days than most monitored US counties. Ranked 727 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly particles: smoke and dust (63% particle days).

The bad-air season here

Most bad days here fall in June and July and April. 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 18 bad days a year; in 2016 to 2025, under 1. The air has improved. The worst recent year was 2023, with 4 bad days on 363 monitored days.

Date	AQI	Main pollutant
2023-06-28	159	PM2.5
2023-06-29	155	PM2.5
2016-06-14	126	Ozone
2018-06-16	119	Ozone
2023-06-07	108	PM2.5

An ordinary day in Boyd

Across 3,643 monitored days from 2016 to 2025, the air in Boyd County rated Good on 68% of them, less often than the 72% typical of monitored counties, and Moderate on 32%. The median day sat at AQI 44; one day in ten went above 59.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)67%2,453 days
ozone31%1,144 days
nitrogen dioxide1%38 days

Every recent year on file

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	365	292	73	0	0	39	97
2024	365	275	90	0	0	42	93
2023	363	226	133	4	2	46	159
2022	365	252	113	0	0	43	80
2021	360	231	128	1	0	44	102
2020	366	285	81	0	0	41	89
2019	365	259	106	0	0	44	74
2018	364	245	118	1	0	44	119
2017	365	223	142	0	0	47	87
2016	365	174	189	2	0	51	126
2015	365	195	167	3	0	49	108
2014	365	247	117	1	0	43	115
2013	365	248	116	1	0	43	119
2012	366	221	137	8	0	46	143
2011	362	203	156	3	0	46	129
2010	365	173	188	4	0	52	119

*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.