Bad Air Days in Charles County, Virginia: under 1 a Year

under 1 bad air day a year

Rare: among the cleanest-air counties EPA monitors. Ranked 783 of 996 monitored counties, where 1 is worst.

What makes them bad: a mix of particles and ozone (50% particle days).

Which months to watch

Most bad days here fall in June and April 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.

Better or worse than it was

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 3 bad days on 365 monitored days.

Date	AQI	Main pollutant
2023-06-29	151	PM2.5
2023-06-07	122	PM2.5
2023-06-08	118	PM2.5
2016-04-19	112	Ozone
2018-06-18	105	Ozone

Most days, not the worst ones

Across 3,613 monitored days from 2016 to 2025, the air in Charles County rated Good on 89% of them, more often than the 72% typical of monitored counties, and Moderate on 11%. The median day sat at AQI 34; one day in ten went above 51.

The pollutant setting the AQI on an ordinary day here:

ozone51%1,851 days
fine particles (PM2.5)32%1,146 days
nitrogen dioxide17%616 days

Charles County by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	364	323	40	1	0	35	101
2024	366	325	41	0	0	36	75
2023	365	273	89	3	1	40	151
2022	356	336	20	0	0	33	74
2021	365	332	33	0	0	34	95
2020	364	347	17	0	0	31	67
2019	356	321	35	0	0	36	90
2018	356	319	36	1	0	33	105
2017	364	320	44	0	0	34	80
2016	357	323	33	1	0	32	112
2015	350	306	43	1	0	34	112
2014	349	296	51	2	0	37	122
2013	360	315	44	1	0	32	150
2012	366	302	56	8	1	37	174
2011	354	272	72	10	2	38	197
2010	365	246	111	8	0	41	147

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

Virginia 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.