UW Study Finds 89% Of King County Masked Up In Public

SEATTLE — A new study released this week found overwhelming compliance with Washington's mask mandate over the last four months in King County. Researchers with the University of Washington, Public Health - Seattle & King County and the state Department of Health found 89 percent of people in King County wore face coverings over their mouth and nose in public on average.

Research teams observed thousands of people in public between November and February to help identify venues where mask use was less common and help officials find areas of improvement to craft better public health messaging.

"There are lots of reasons why people might not feel comfortable or might not want to wear a mask," said Marissa Baker, an assistant professor who participated in the study. "The goal is to determine where pockets of lower compliance are, and then to use that information to develop appropriate risk communication for those locations."

The study included nine student volunteers from the UW School of Public Health to observe 40 venues in seven regions across King County. The areas chosen included parks, malls, Sea-Tac Airport, and grocery, convenience and hardware stores. Observers spent about 30 minutes in each place and took notes on the people around them, marking down mask use and estimates on age and gender.

Overall, researchers said mask compliance ranged between 85 percent and 95 percent countywide. The highest compliance was seen among people entering hardware and grocery stores, averaging between 94 and 97 percent. Venues on the low end, between 74 and 84 percent, included convenience stores and transit centers.

On the demographics side, observers noted the lowest use among children between 2 and 11 years old, and higher in all other age groups, ranging between 85 and 90 percent. The study found women were slightly more likely to wear masks, at 91 percent, compared to men, at 86 percent.

"The data show that differences in how well people are masking aren't easily explained by geography alone," said Cathy Wasserman, an epidemiologist at the Department of Health. "Instead, the results suggest that masking behaviors may be influenced by intersecting factors such as location and activity, as well as individual characteristics like age and sex."

Health officials said consistent and proper use of facial coverings continues to play a major role in preventing transmission, even as vaccinations become more widespread.

"COVID-19 spreads through the air, and the risk is highest in crowded and indoor space with poor ventilation," said Dr. Jeff Duchin, health officer for King County. "COVID-19 remains a serious threat, and wearing masks while indoors and in public spaces when around others protects both ourselves and each other."

Duchin said his goal is to see mask usage "well over 90%" across the county.

Learn more about best practices for face coverings on the Public Health Insider blog.