The message from Costco’s CEO is straightforward and to the point.

“Effective Nov. 16, 2020, we will require all members, guests and employees to wear a face mask or face shield at Costco locations,” writes Craig Jelinek, President and CEO Costco Wholesale on the company’s COVID-19 webpage.

Costco has had a face mask policy in effect since May 4, 2020, but shoppers who declined to wear a mask due to medical conditions were exempt.

That will no longer be the case.

Costco CEO’s Message

The rest of Jelinek’s message explains some of the company’s reasoning behind the change.

“This updated policy may seem inconvenient to some, however we believe the added safety is worth any inconvenience. Our goal is to continue to provide a safe shopping environment for our members and guests, and to provide a safe work environment for our employees. Thank you for your cooperation and support,” says Jelinek.

Fresno’s Top Doc Responds

Dr. Rais Vohra, Fresno County’s interim health officer, says face shields are not a substitute for masks, but they may provide some eye protection.

“The mask provides the best barrier against coronavirus, influenza, and other wintertime viruses,” says Vohra to GV Wire℠ by email. “If a face shield is used, make sure it is long, wraps around the sides of the face, and preferably has a drape along the bottom that can catch droplets and keep them from getting out.”

CDC & Face Shields

The federal Centers for Disease Control and Prevention says a face shield is primarily used for eye protection for the person wearing it.

“At this time, it is not known what level of protection a face shield provides to people nearby from the spray of respiratory droplets from the wearer,” the CDC states on its website. The CDC goes on to say there is currently not enough evidence to support the effectiveness of face shields for source control. Therefore, the CDC does not currently recommend use of face shields as a substitute for masks.

Although evidence on face shields is limited, according to the CDC the available data suggest that the following face shields may provide better source control than others:

• Face shields that wrap around the sides of the wearer’s face and extend below the chin.
• Hooded face shields.

Aerosolized Droplets Move Around Visor With Ease

Researchers from Florida Atlantic University used visualizations to test how face shields and masks with valves perform in impeding the spread of aerosol-sized droplets.

The July study published in the journal Physics of Fluids, used visual demonstrations and photos to using a laser light sheet and a mixture of distilled water and glycerin to generate the synthetic fog that made up the content of a cough-jet.

“From this latest study, we were able to observe that face shields are able to block the initial forward motion of the exhaled jet, however, aerosolized droplets expelled with the jet are able to move around the visor with relative ease,” said Manhar Dhanak, Ph.D., department chair, professor, and director of SeaTech, who co-authored the paper. “Over time, these droplets can disperse over a wide area in both lateral and longitudinal directions, albeit with decreasing droplet concentration.”

The researchers say that the key takeaway from this latest study illustrates that face shields and masks with exhale valves may not be as effective as regular face masks in restricting the spread of aerosolized droplets.