Observed face mask use outside retail chain stores during the COVID-19 pandemic in two cities in the state of Idaho, USA.

During the COVID-19 pandemic, public health authorities have encouraged the use of face masks to minimize transmission within the community. To assess mask wear during a COVID-19 surge and guide public health response efforts, including public messaging on mask recommendations, we compared observed mask use in the largest city in each of Idaho's 2 most populous counties, both without a current mask mandate. We recorded mask usage by every third person exiting stores of 5 retail chains in Boise and Nampa during November 8–December 5, 2021. Observations were conducted during three time periods (morning, afternoon, and evening) on weekday and weekend days. A multivariable model with city, retail chain, and city-chain interaction was used to assess mask wear differences by city for each chain. Of 3021 observed persons, 22.0% wore masks. In Boise, 31.3% (430/1376) of observed persons wore masks; in Nampa, 14.3% (236/1645) wore masks. Among all persons wearing masks, > 94% wore masks correctly; cloth and surgical masks were most common. By retail chain, observed individuals at Boise locations were 2.3–5.7 times as likely to wear masks than persons at respective Nampa locations. This study provided a rapid, nonconfrontational assessment of public use of mitigation measures in 2 Idaho cities during a COVID-19 surge. [ABSTRACT FROM AUTHOR]