Masks with breathing valves, in particular, are being marketed as a better option than plain cloth coverings—but they don’t work to prevent COVID-19 transmission the same way simple masks can.

“The purpose of masks is to keep respiratory droplets from reaching others to aid with source control. Masks with one-way valves or vents allow exhaled air to be expelled out through holes in ...

Cloth masks act as “source control” to block virus particles exhaled by the wearer and provide “filtration for personal protection” by blocking incoming infectious droplets from others ...

So, masks were only used for source control when people had symptoms of COVID-19 or were identified as high-risk due to their travel history. But everything changed when it became clear the virus was ...

Masks function very differently as personal protective equipment (PPE) versus source control. Masks are very good at blocking larger droplets and not nearly as good at blocking tiny particles.

Masks may be more effective as a “source control” because they can prevent larger expelled droplets from evaporating into smaller droplets that can travel farther. Another factor to remember, noted ...

The community use of masks for source control is a “public good”: something we all contribute to that eventually benefits everyone—but only if almost everyone contributes, which can be a ...

CDC urges indoor mask use amid COVID-19 surge 03:47. The CDC on Friday issued its strongest mask guidance yet during the COVID-19 pandemic, calling for "universal mask wearing" in all activity ...

Employees wearing masks and face shields are seen at the Railway Museum on the first day of re-opening on June 10, 2020, in Saitama, Japan. Takashi Aoyama / Getty Images ...

Some breathable face masks don’t do much to protect against spreading the coronavirus, health officials have warned. Face coverings with valves or vents — largely worn in pre-pandemic times b… ...

“The CDC now says the purpose of masks is to keep respiratory droplets from reaching others to aid with source control. However, masks with one-way valves or vents allow air to be exhaled ...

Cloth masks act as “source control” to block virus particles exhaled by the wearer and provide “filtration for personal protection” by blocking incoming infectious droplets from others ...