Enumclaw summer ozone levels suck. Blame Seattle, the heat, and the Cascades

Data shows the 98022 ZIP code area experienced the second-highest per capita asthma-related emergency department visits in 2022. Here’s why.

Enumclaw had the second-highest emergency department visits for asthma-related incidents in 2022, Public Health — Seattle & King County reported earlier this year.

Public Health published several data dashboards about how climate change might be affecting the health of King County residents in late January, tracking emergency department visits for heat- and cold-related illnesses, seasonal allergies, food and waterborne illnesses, and asthma.

“In the Pacific Northwest, climate change is leading to longer, hotter summers and more intense wildfire seasons. These weather events have a wide range of impacts on our health, both short-term and long-term,” the Public Health Insider article announcing the dashboards read. “Gathering information on these health impacts in our community will allow us to understand trends over time, identify disparities in who is most impacted, establish potential areas for action, and inform future planning and investment.”

Most of the dashboards only examine data for north, east, and south King County, plus Seattle, meaning data for the 98022 ZIP code and Enumclaw specifically were not available. However, asthma-related emergency department data was broken down by ZIP code, and the southern-most King County city almost came out on top.

According to Public Health, Enumclaw saw almost 2,500 emergency department visits per 100,000 people — which roughly translates to 567 ED visits in 2022.

The only area that had more was Auburn, in the 98002 ZIP code area specifically, which experienced a total of nearly 1,000 ED trips.

For additional comparison, 98045 (North Bend) had a ED visit per capita rate of about 906; 98010 (Black Diamond), a rate of 1,250 per 100,000 people; and 98051 (Ravensdale, Kanaskat) had a per capita rate of just over 2,075.

Why Enumclaw experienced such a higher rate of asthma-related ED visits might surprise you: out of the three major metrics Public Health’s Manager of Community Health worker and asthma program — access to primary care, housing/indoor air quality, and outdoor air quality — it appears that the main contributing factor to asthma-related ED visits was poor outdoor air.

According to Jan Capps, a King County Public Health community health worker manager, said that in general, Enumclaw residents’ per capita access to primary care is about on par with King County. Housing/indoor air quality (which covers moisture, mold, dust mites, poor ventilation, etc.) is also pretty much equal to King County as a whole.

Finally, in general — and this is likely not a bombshell realization — Enumclaw’s outdoor air quality is superior to the rest of the counties most of the year.

But according to Capps and Erik Saganić, technical analysis manager at the Puget Sound Clean Air Agency, the summer months sees chemicals travel from Tacoma and Seattle to Enumclaw and, because of the city’s proximity to the Cascade mountains, gets trapped in the area. Throw in some hot weather into the mix, and now you have ozone, which exacerbates asthma and other respiratory conditions.

Ozone (colloquially called “smog”) is a chemical formed from a mix of nitrogen dioxide (from the combustion of fossil fuels) combined with organic compounds (examples include tree pollen or smoke) and UV light.

“You need a chemical reaction to form ozone — and it doesn’t happen right out of a tailpipe. It takes time and happens downwind from the major cities,” Saganić said in an email interview, adding that the threshold for ozone to form is about 85 degrees. “… the reason high heat is important is because trees are under stress and emit more organic compounds into the air at a higher rate.”

Public Health’s data didn’t record when locals went to the ED for their asthma, Capps said, which means it’s impossible to say for sure that unhealthy ozone levels in the summer contributed to Enumclaw having the second-highest rate of asthma-related ED visits.

However, Clean Air Agency data from 2022 shows that Enumclaw had more ozone than ten other sites where ozone levels were recorded, which include Issaquah, Lacey, Mount Rainier, and Seattle Beacon Hill; that year, Enumclaw’s average ozone levels just met national standard line that separates good ozone quality from bad ozone quality.

Contributing to this might have been record-setting heat in July, when when weatherspark.com recorded six consecutive days of 90 degree-plus heat at the SeaTac Airport, as well as wildfires.

But that’s not the whole story, since between 2004 and 2022, Enumclaw’s average ozone levels was consistently higher than the other ten sites. The only exception was in 2004 and 2005, when North Bend had an equal average ozone level.

Additionally, Enumclaw’s ozone levels exceeded national standard between 2004 and 2010, as well as 2017 through 2019.

In general, the Clean Air Agency recorded 16 total days of unhealthy levels of ozone for sensitive groups in King County in 2022, as well as four days of “unhealthy” ozone levels and one days of “very unhealthy” levels.


According to Capps, King County has a two-pronged approach to help residents improve their living situation — at least when it comes to asthma and other respiratory conditions.

First, the King County Housing Authority helps low-income renters and home owners improve indoor air quality in their living space by providing HVAC repairs and improvements, among other resources. That’s a general program for folks with and without respiratory issues — but those suffering from severe asthma are often referred to Public Health’s free “national award winning” Community Health Worker Asthma Resources program for additional aid.

This program provides education, support, and, maybe most importantly, “trigger reduction” supplies for people with severe asthma, Capps said — those supplies include mattress and pillow covers to reduce dust mites, HEPA vacuums that use special bag filters to keep particulates out of the air, food storage containers, and cleaning kit without harsh chemicals.

“Basically, the King County Housing Authority does the physical improvements to the home, and then we support those clients who have asthma with the education support and trigger reduction [supplies],” Capps said.

Most people are referred to Public Healths’ program by medical providers, but you can also refer yourself at redcap.link/kingcountychwprogram; those who self-refer will have to fill out an eligibility form before receiving support.

You can also learn more about King County Housing Authority’s energy improvement program at www.kcha.org/residents/subsidized/energy.

Washington State Department of Health data showed that the 98022 ZIP code area had the second-most emergency department visits for asthma-related issues in 2022. This is in part to Enumclaw’s unique geography that traps ozone in the area during hot days.

Screenshot Washington State Department of Health data showed that the 98022 ZIP code area had the second-most emergency department visits for asthma-related issues in 2022. This is in part to Enumclaw’s unique geography that traps ozone in the area during hot days.