OLYMPIA — Washington residents will be required to wear masks in public starting Friday as a way to slow the spread of COVID-19.

Gov. Jay Inslee announced a statewide public health order for residents to wear face coverings in public settings and businesses to require masks in their premises for employees and customers.

The order, from Washington Health Secretary John Wiesman, includes everyone over 5 years old, with an exception for the deaf or hard of hearing while communicating with someone else and those who have a medical condition that makes wearing a mask difficult. Children 3 to 5 years old are recommended but not required to wear face coverings and those 2 and under should not wear face coverings.

The mask should fit snugly around the mouth and nose, said Wiesman, who added he sometimes sees people with masks covering their mouth, but not their nose.

“We simply have to take these different measures right now,” he said.

People involved in outdoor recreation alone or with members of their households can remove masks, but have them available to put on if they come into contact with others. People seated at restaurants need not wear masks but should observe social distancing rules.

Residents are also advised to continue with other precautions: maintain 6 feet of distance with others in public, wash hands frequently, get tested for COVID-19 when experiencing other symptoms, and stay home when sick.

While violating the “mask up” order is technically a misdemeanor, Inslee said the state will rely on voluntary compliance, peer pressure and “the fact that we care for our loved ones.”

“It is not our desire to have hard-working officers following people around on mask issues,” Inslee said during a news conference to announce the orders.

But the state will add more restrictions in Yakima County, the site of the worst outbreak of the virus in the state, where the rate of infection is among the worst in the country and some 27 times higher than the rate in King County.

In Yakima County, businesses that don’t require employees to wear face coverings, or that continue to serve customers or patrons who don’t wear masks, will be contacted by state agencies that have authority over their licenses. If, after repeated warnings, a business doesn’t comply with masking requirements, it could lose its license to operate. Further enforcement measures could lead to civil or criminal penalties.

Businesses faced similar enforcement measures during the partial shutdown of the state’s economy, but they rarely were necessary, Inslee said.

The state could extend the tougher orders beyond Yakima to other counties where infection rates are rising and “the medical system could potentially be compromised because of the surge in cases,” Inslee said. The state has the greatest concerns now about Benton and Franklin counties, which are also seeing sharp increases.

“We’ve seen some increasing activity in Adams and Spokane County, so we’re watching that very carefully,” he said.

The order to require face coverings for most people in most public settings could remain in place until a vaccine or a cure is available for COVID-19, Inslee said. The virus is unpredictable, so it’s possible something like a change in temperature, humidity or another factor could drive it down and lead to a relaxation of the masking order, he said.

“I would think it’s likely that this would remain in place until there’s some other avenue or some other tool that comes along. I don’t exactly know what that would be, though,” he said.

Recent studies have shown that wearing masks help reduce the spread of the virus, offering some protection to the person who is wearing the face covering and people with whom that person comes into contact, Wiesman said.

For the news conference, Inslee and Wiesman were joined by video connection with Craig Jelinek, chief executive officer of Costco, who said that retail chain, which stayed open during the partial shutdown, instituted a masking policy in May to protect its employees and customers.

“It was not a popular decision (with customers) at first,” Jelinek said. But because the store serves members who pay a fee, it was able to give customers the choice of wearing a mask or not being allowed to shop, he said.

In recent weeks there have been fewer complaints, he added.