States and counties across the nation are asking citizens to wear masks in public to curb the spread of the coronavirus. Now, counties in California’s Bay Area our following suit, with one important distinction: masks with valves are not to be considered adequate protection from the sickness.
On April 22, several counties in Northern California put into effect orders for citizens to wear masks in public. These included San Francisco, San Mateo, Alameda, Contra Costa and Marin counties, according to The Mercury News. They joined Los Angeles and Sonoma counties, who had made similar orders the week prior.
The newer mask orders, however, carried stipulations missing from previous ones. According to the orders, masks with valves, including some models of N95 mask, will not be considered compliant. These masks filter particles from air flowing into the mask, but not flowing out. As such, they don’t filter the wearer’s breath and don’t protect those around the wearer from virus particles.
San Mateo County’s announcement of the order explicitly excluded masks with valves from use. “Note that any mask that incorporates a one-way valve (typically a raised plastic cylinder about the size of a quarter on the front or side of the mask) that is designed to facilitate easy exhaling is not a Face Covering under this Order and is not to be used to comply with this Order’s requirements,” the order read. “Valves of that type permit droplet release from the mask, putting others nearby at risk.”
Protecting Others From Infection
“Given that most of the value of these masks is not to protect the wearer but to protect others from a potentially contagious asymptomatic wearer, those one-way valves make the masks practically useless for protecting others,” cardiologist Dr. Matthew Springer told the San Francisco Chronicle earlier this month.
Meanwhile, the Centers for Disease Control and Prevention (CDC) have recommended against hospitals using N95 masks that have exhalation valves. “Respirators with exhalation valves should not be used in situations where a sterile field must be maintained (e.g. during an invasive procedure in an operating or procedure room) because the exhalation valve allows unfiltered exhaled air to escape into the sterile field.”
As for what can be used to comply with the Bay Area’s mask order, San Mateo County provides a few recommendations. “Examples of Face Coverings include a scarf or [bandana]; a neck gaiter; a homemade covering made from a t-shirt, sweatshirt, or towel, held on with rubber bands or otherwise; or a mask, which need not be medical-grade.”