Bad Air Days in Clark County, Nevada: 29 a Year

29 bad air days a year

Among the worst tenth of monitored US counties. Ranked 18 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly ozone: summer smog (21% particle days).

The bad-air season here

Most bad days here fall in July and June and August. Averaged over 2016 to 2025.

What actually helps here

Particles (wildfire smoke, dust) cause enough bad days here to matter. A HEPA purifier sized to your bedroom removes them; run it with windows shut on bad days.
Upgrade the furnace or AC filter to MERV 13 so the whole house is filtered, not just one room.
Ozone drives many bad days here. Purifiers and filters do not remove ozone, so do not buy one for that. Ozone peaks on hot afternoons: exercise outside in the morning.
Sign up for EnviroFlash ozone alerts for this area during the worst months.

The worst days on file

In 2000 to 2009 this county averaged 55 bad days a year; in 2016 to 2025, 29. The air has improved. The worst recent year was 2018, with 49 bad days on 365 monitored days.

Date	AQI	Main pollutant
2022-09-08	480	PM10
2022-09-09	351	PM10
2016-07-30	268	PM10
2022-04-11	260	PM10
2022-10-22	197	PM10

An ordinary day in Clark

Across 3,653 monitored days from 2016 to 2025, the air in Clark County rated Good on 27% of them, less often than the 72% typical of monitored counties, and Moderate on 66%. The median day sat at AQI 62; one day in ten went above 97.

The pollutant setting the AQI on an ordinary day here:

ozone60%2,187 days
fine particles (PM2.5)34%1,231 days
coarse dust (PM10)4%145 days
nitrogen dioxide2%89 days

Clark County by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	365	113	226	26	0	61	138
2024	366	90	236	40	1	64	170
2023	365	106	233	26	1	61	197
2022	365	71	268	26	6	64	480
2021	365	87	244	34	3	62	183
2020	366	92	249	25	3	65	174
2019	365	128	232	5	0	58	122
2018	365	104	212	49	1	63	155
2017	365	100	236	29	1	61	154
2016	366	79	261	26	1	61	268
2015	365	90	252	23	1	61	151
2014	365	72	277	16	2	61	160
2013	365	68	259	38	4	63	166
2012	366	68	245	53	6	66	180
2011	365	106	210	49	2	58	161
2010	365	118	214	33	0	58	147

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

Nevada 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.