Olympic Region Clean Air Agency

08/10/2026

Good morning and happy Monitoring Monday.

Last week, smoke from eastern Washington and British Columbia drifted into western Washington for several days and turned PM2.5 (particulate) air monitors and sensors across the region orange (unhealthy for sensitive groups) and red (unhealthy). Luckily for us, it only lasted a few days. Along with atmospheric particulate matter, the smoke also brought pollutants that increased ambient ozone concentrations in the area.

Ozone formation occurs when heat, sunlight (UV index), nitrogen dioxide (NO2) and volatile organic compounds (VOC) are high and winds are low. Assuming NO2 and VOC emissions are similar from day-to-day, ozone prediction models primarily rely on the weather forecast. The following plot compares August 6th and August 7th. Wind speed was very low on both days. Ambient temperature on the 6th was higher than on the 7th, but not enough to explain the drastic difference in ozone concentration observed on these two days.

The primary difference? A significant amount of smoke remained in our region on the 6th, amplifying ozone formation far above what we usually see here.


https://science.nasa.gov/earth/nasa-funded-study-shows-wildfire-smokes-hidden-ozone-toll/

08/05/2026

When businesses care about air quality, we like to recognize them. This week, ORCAA awarded Tacoma-based Dickson Demolition & Abatement with our "Taking Care of the Air" award.

The Olympic Region Clean Air Agency enforces clean air laws in Clallam, Grays Harbor, Jefferson, Mason, Pacific, and Thurston Counties.

08/03/2026

Today our thoughts are with our friends, family, and colleagues in eastern Washington as they deal with unprecedented fires, lost homes, and the worst air quality in the nation. We are fortunate to live where onshore winds and higher humidity typically keep smoke at bay and our forests somewhat resistant to devastating wildfires.

That said, shifting winds will likely bring smoke to our region over the next few days. Please see our blog post for more information regarding the forecast and how to best prepare.

The Olympic Region Clean Air Agency enforces clean air laws in Clallam, Grays Harbor, Jefferson, Mason, Pacific, and Thurston Counties.

07/27/2026

It's Air Monitoring Monday!

Last week was all about SensWA air sensors. We installed one in Belfair at North Mason Regional Fire Authority Station 21 and one at the Montesano Fire Department.

Both sensors have been added to the ORCAA air quality network map, as well as the Dept of Ecology’s air quality map. These new sensors are part of an ongoing project to expand air quality monitoring in all 6 of our counties. When finished, all of ORCAA’s counties will have one primary monitor and 2 additional SensWA units.

Shout out to both crews for hosting an air quality sensor and accommodating us on the installation. I also found a new friend living on one of our sensors. I’m glad she didn’t surprise me, or that sensor might have been accidentally thrown off the roof. Also, she and others like her are the reason there are screens over the sensor openings.

07/20/2026

While conducting monthly maintenance on our BAM 1022 last week, it occurred to me that some very, very small percentage of you might be curious about how we measure PM2.5, a.k.a. fine particulate matter, in the atmosphere.

There are actually several methods, but today consider the BAM. You can say it like Emeril the chef if you'd like. It's more fun. BAM is an acronym for Beta Attenuation Monitor. Yep. Beta as in the beta radiation emitted by carbon 14. Don’t worry, it's a tiny amount, contained, and poses no danger to anyone. There are two key elements to these measurements.

The first challenge (shown in the left-side diagram) is separating the particles with diameters smaller than 2.5 micrometers (PM2.5) from larger atmospheric particles. It’s the little ones that cause the most health problems and therefore the ones we want to measure. We do this by passing the air sample through a twisty, turny path, which causes all the larger particles to become trapped and removed from the air sample. The remaining PM2.5 particles are collected on the filter strip (shown in the right-side diagram).

The beta radiation passes through the filter and is absorbed by the particles (also shown in the right-side diagram). More particles absorb more radiation. As the detector sees less radiation getting through the filter, the monitor converts the “attenuated,” i.e., decreasing signal, into an equivalent mass of particles. That mass divided by the volume of air passing through the filter gives us the concentration of particles in the air. So for those of you still reading AND awake, congratulations, you learned a little about ambient air monitoring.

Oh, and the internal diagrams of the PM10 and PM2.5 cyclones were taken from this publication https://doi.org/10.1080/027868200303669

Check it out if you want to read more about particle size selection physics, which could be true if you're still actually reading this post.

07/13/2026

An already active wildfire season could heat up this week! Temperatures across Washington are forecast to rise into the 80s (°F) in western Washington and well into the 90s in eastern Washington. That means existing wildfires could expand and new fires could get started. Watch the Washington Smoke Blog for updates and information on current smoke forecasts. https://wasmoke.blogspot.com

07/06/2026

Some communities in ORCAA's region experienced spikes in particulate matter pollution over the weekend. These spikes started late Saturday afternoon and were clearly related to residential fireworks. Some of the elevated pollution levels lingered well into Sunday morning. Fortunately, by Sunday midday, the smoke cleared and our air quality returned to good levels.



https://www.orcaa.org/air-quality/current-air-quality/

07/02/2026

Each year, we celebrate our national birthday with colorful explosions as fireworks ignite around American neighborhoods on the Fourth of July.

These displays provide brilliant light shows each Independence Day, but they also cause spikes in air pollution levels that may be hazardous to the health of individuals. The Olympic Region Clean Air Agency (ORCAA) sees elevated levels of fine particulate matter (PM2.5) air pollution at many of its monitoring stations each Independence Day. In some cases, levels at the monitoring sites reached hazardous air quality!


https://www.orcaa.org/celebrate-with-clean-air-this-fourth-of-july/

06/29/2026

Yelm SensWA air sensor. FIXED!
Port Townsend air monitor. FIXED!
ORCAA air monitoring team just knocked it out of the park last week.

06/22/2026

Air monitoring on the Olympic Peninsula is both amazing and challenging. We get to visit so many beautiful spots while driving to and from sites. That said, equipment doesn't always work properly, and it can be incredibly frustrating when a site requires an immediate return visit that eats up a whole day. This recently installed SensWA air sensor never established communication and needs to be fixed or replaced as soon as possible. That said, our recent beautiful weather definitely takes away some of the sting.