Wear a mask in public. It’s a no-brainer — for yourself and everyone around you.

Costco and JetBlue, which serves Seattle-Tacoma International Airport, made the right moves in requiring all customers and passengers to wear face coverings. So were subsequent announcements that Seattle-based Alaska Airlines and the rest of the nation’s major air carriers will require all on board to mask up.

Such private-sector leadership in establishing masks as a new social norm shores up support for critical protective measures as many sectors of society grow restive about self-isolation. 

Social distancing has effectively slowed the spread of coronavirus, according to scientific analysis. Gov. Jay Inslee and other governors were right to implement social restrictions, but public health could be at risk as some people’s weariness cuts into support for limitations.

At least eight eastern states and Hawaii require masks for anyone who’s out and about. Inslee so far hasn’t taken that step, but businesses and communities should help make mask-wearing a grassroots cause.

The Centers for Disease Control and Prevention and Washington’s Department of Health each recommend people wear cloth masks away from home. Health scientists have found in several studies that even homemade masks provide some protection. They help limit the particle dispersion from coughs, sneezes and exhalations. Because COVID-19 can seemingly be spread by people who never experience symptoms, all people who are able, sick or strong, should wear masks in public. Grocery-store trips, mass transportation and waiting rooms all unavoidably bring people into tight shared spaces.

Masks can be hard to come by for many households. Disposable masks are back-ordered from many suppliers. Sewing machines are tricky to master, and store-bought cloth masks cost money. Whole Foods announced Thursday that it would give disposable masks to all shoppers, which is a canny way to attract customers and an excellent public-health contribution. Church and community groups throughout Washington have stepped up with mask donations, some via a drive organized by Lt. Gov. Cyrus Habib.

These efforts deserve praise, as does every resident who masks up whenever heading out during this time of great need. Wear a mask.