Air quality in Cowlitz County, WA

Q: How often is the air bad in Cowlitz County?

From 2021 to 2025, monitors in Cowlitz County recorded almost no bad-air days a year with an AQI above 100, which is unhealthy for sensitive groups or worse. The worst year in that stretch was 2022, with 2 bad-air days.

Q: Where can I see today's air quality in Cowlitz County?

AirNow, run by the EPA and its partners, shows the current AQI and tomorrow's forecast for your ZIP code. Its fire and smoke map adds smoke plumes. On a typical day the AQI in Cowlitz County is about 22, which is good, fine for everyone. Check it most in August, September and October, when bad days here cluster.

Includes Longview and Kelso · EPA monitor readings, 2021 to 2025 (fine particles only) · 111,000 people

Clean most daysOnly particles are measured

For today's air and tomorrow's forecast, check AirNow by ZIP code.

Bad-air days a year

day with an AQI over 100

2 bad-air days in 5 years of readings, 2021 to 2025. Cowlitz County has the 3rd fewest bad-air days of the 29 Washington counties with monitors.

0days unhealthy for everyoneAQI over 150, a year

22AQI on a typical dayGood: fine for everyone

Aug to Octworst monthsFine particles, the only pollutant measured

282worst day since 2016Sep 13, 2020, fine particles

How to read the AQIThe EPA's air score runs from 0 to 500. Higher is worse. Over 100 counts as a bad-air day.

Typical day 22 (Good)Worst day 282 (Very unhealthy)

Good0 to 50Moderate51 to 100Sensitive groups101 to 150Unhealthy151 to 200Very unhealthy201 to 300Hazardous301 to 500

When bad air happens in Cowlitz County

Average bad-air days in each month, from 10 years of daily readings since 2016. Most fall in August, September and October. Only fine particles are measured here.

Jan0

Feb0

Mar0

Apr0

May0

Jun0

Jul0

Aug0.6

Sep0.9

Oct0.2

Nov0

Dec0

Fine particles (smoke, soot)Ozone (smog)Bars stack in that order, from the bottom.

See the numbers by month

Average bad-air days a year in each month in Cowlitz County, from 10 years of daily readings
Month	Fine particles	All
January	0	0
February	0	0
March	0	0
April	0	0
May	0	0
June	0	0
July	0	0
August	0.6	0.6
September	0.9	0.9
October	0.2	0.2
November	0	0
December	0	0

The worst day since 2016 was September 13, 2020: AQI 282, from fine particles.

What causes it

Fine particles are the only pollutant measured here. Most of the bad days here came in one stretch: 9 fine-particle days in September 2020. Monitors here don't measure ozone, so smog days aren't in these counts.

CDC's model estimates about 0.0 days a year with high ozone at the county's worst spot, 2018 to 2022. See the estimates on the map

CDC estimates by month, 2001 to 2022

The CDC's model counts bad-air days at the county's worst spot, from monitors and satellites. Particles (brown) fill the inside of the ring and ozone (blue) the outside.

See it on the map Compare with Clark County Smoke or smog?

See the numbers by month

CDC estimated bad-air days a year in each month in Cowlitz County, 2001 to 2022
Month	Fine particles	Ozone
January	0	0
February	0	0
March	0	0
April	0	0
May	0	0
June	0	0.1
July	0	0.1
August	0.5	0.2
September	0.5	0
October	0.2	0
November	0	0
December	0.1	0

What helps in Cowlitz County

Monitors here track fine particles such as smoke, so filtering the air at home helps most. Check the forecast for ozone, which isn't measured here.

Keep one room clean on smoky days

Shut the windows and run an air purifier sized for the room.

Choosing a purifier →

Upgrade the furnace filter

Use MERV 13 if your system can take it, and run the fan on smoky days.

Furnace filters →

Check tomorrow's forecast

AirNow posts an air quality forecast by ZIP code, usually the day before.

AirNow →

For today's reading and tomorrow's forecast, check AirNow by ZIP code. Its fire and smoke map adds smoke plumes.

Purifiers with a verified smoke rating

For a clean room on smoky days. Each has a smoke CADR tested by AHAM's independent program and is certified by California as a mechanical cleaner, so it makes no ozone.

Bedroom or small room

Levoit Vital 100S-P

143 smoke CADR

Everyday: up to 222 sq ft
Heavy smoke: up to 143 sq ft
Filters: about $40 a year

The cheapest unit we found with a verified smoke rating. Enough for a bedroom clean room.

$119.99 at Levoit

Best value for smoke

Levoit Vital 200S-P

250 smoke CADR

Everyday: up to 388 sq ft
Heavy smoke: up to 250 sq ft
Filters: about $50 a year

The most verified smoke cleaning per dollar of any qualifying model: 75% more than the 100S-P for $50 more.

$169.99 at Levoit

Living room or open floor

Levoit Core 600S-P

391 smoke CADR

Everyday: up to 606 sq ft
Heavy smoke: up to 391 sq ft
Filters: $60 to $120 a year

For a big room or a small apartment. Buy the LAP-C601S-WUS version, which CARB lists as mechanical.

$299.99 at Levoit

Why all 3 are Levoit: of the models we checked that pass both tests, these give the most verified smoke cleaning per dollar at each room size. Medify's MA-25 and MA-40 also pass but cost more for the same cleaning.

Ratings from the AHAM Verifide directory and CARB's certified list. Prices from Levoit's site, checked November 7, 2026; they change. We don't earn anything from these links. How to pick a purifier

Every year since 2003

Bad-air days each year. The striped part is days unhealthy for everyone, over AQI 150. The worst recent year was 2022, with 2 bad-air days.

Unhealthy for sensitive groups (101 to 150)Unhealthy or worse (over 150)

See the numbers by year

Bad-air days each year in Cowlitz County
Year	Bad-air days	Over 150
2003	0	0
2004	0	0
2005	0	0
2006	0	0
2007	0	0
2008	0	0
2009	0	0
2010	0	0
2011	0	0
2012	0	0
2013	0	0
2014	0	0
2015	1	0
2016	0	0
2017	2	1
2018	4	2
2019	0	0
2020	9	8
2021	0	0
2022	2	0
2023	0	0
2024	0	0
2025	0	0

Cowlitz County and its neighbors

Bad-air days a year, 2021 to 2025. Washington counties with monitors averaged about 5 bad-air days a year, weighted by population.

Lewis County3

Clark County2

Columbia County1

Cowlitz County<1

Nearest county with a full report: Pierce County, WA (3 bad-air days a year).

Questions people ask about air in Cowlitz County

How often is the air bad in Cowlitz County?

From 2021 to 2025, monitors in Cowlitz County recorded almost no bad-air days a year with an AQI above 100, which is unhealthy for sensitive groups or worse. The worst year in that stretch was 2022, with 2 bad-air days.

What causes bad air in Cowlitz County?

Most of the bad days here came in one stretch: 9 fine-particle days in September 2020. Bad days cluster in August, September and October. Monitors here don't measure ozone, so smog days aren't in these counts.

Where can I see today's air quality in Cowlitz County?

AirNow, run by the EPA and its partners, shows the current AQI and tomorrow's forecast for your ZIP code. Its fire and smoke map adds smoke plumes. On a typical day the AQI in Cowlitz County is about 22, which is good, fine for everyone. Check it most in August, September and October, when bad days here cluster.

About these numbers

Day counts come from the EPA's county air quality summaries, which take the worst reading across a county's monitors each day. Monitors here reported on about 342 days a year from 2021 to 2025. A county is large, and your street can be cleaner or worse. CDC's model, which estimates every county from monitors and satellites, gives the worst spot in Cowlitz County about 4 high-particle days and almost no high-ozone days a year from 2018 to 2022.

Sources: EPA AirData county AQI summaries (2000 to 2025) and daily county AQI (2016 to 2025); CDC Environmental Public Health Tracking Network modeled PM2.5 and ozone (2001 to 2022). Updated November 8, 2026.