Medical Community Warns Public on Masks with Exhalation Valve

Hospitals prohibit masks with exhaust valves inside clinic premises. Here’s why.

A woman demonstrates how to use the N95 respiratory mask, April 28, 2009, in Oakland, California. Photo source: Justin Sullivan/Getty Images

MANILA, Philippines — As the Philippines’ number of COVID-19 cases skyrocket to 63,000 cases, local hospitals such as the Medical City and Makati Medical Center have banned the use of respirators/ masks with exhalation valves.

The Medical City Clinic released a statement on its facebook page warning patients, clinic staff and doctors against the use of mask with exhalation valves. According to the post, masks with valves are designed to ease exhalation and decrease humidity for the wearer, however, they do not block transmission of COVID-19 because they allow exhaled air and droplets to escape.

“We value your safety and the well-being of our patients, clinic staff and doctors. Starting today, all locations of The Medical City Clinic will not allow patients and companions wearing masks with valves to enter clinic premises.”

In a twitter post, Dr. Gia Sison shared Makati Medical Center’s advisory on the use of masks with exhalation valve saying “Masks with valves are NOT advised. Please be guided.”

The advisory cited the Center for Disease Control and Prevention’s guideline on the use of respirators with exhalation valve. The organization explained that an N95 respirator with an exhalation valve provides the same level of protection to the wearer as one that does not have a valve. “However, respirators with exhalation valves should not be used in situations where a sterile field must be maintained because the exhalation valve allows unfiltered exhaled air to escape into the sterile field.”

The purpose of the Centers for Disease Control and Prevention’s universal masking guidelines is to prevent viral transmission from infected individuals to people around them. However, masks with valves take potential coronavirus droplets into the environment around the wearer, defeating the mask’s one important purpose — protecting those around you.

“Any person who is in close contact with someone who has respiratory symptoms is at risk of being exposed to potentially infective respiratory droplets. To protect the safety of patients, staff and visitors, masks with exhalation valves/vents are not allowed in the hospital in the context of the COVID-19 pandemic,”

makati medical center advisory on masks with valve

“To protect the safety of patients, staff and visitors, masks with exhalation valves/vents are not allowed in the hospital in the context of COVID-19 pandemic. If you come to MMC with a mask with vents, you will be asked to replace your mask with surgical mask,” it said.

 Dr. Ali Raja, executive vice chair of the department of emergency medicine at Massachusetts General Hospital and an associate professor at Harvard Medical School, in an interview with, said that “The virus can be transmitted through the valves, which offer no filtration at all.” He said that the mask with a one way valve protects the wearer but does not protect the people around.

“Any mask with a one-way valve is only going to protect the person wearing it. It won’t protect anyone around that person from potential exposure to virus particles they exhale…It may give the people surrounding them a false sense of security.”

William Schaffner, MD, professor of preventive medicine and infectious disease at Vanderbilt University Medical Center, quoted by abcnews, said “We want to protect you from me. And so, this valved N95 [mask] really doesn’t function appropriately in this COVID environment– either in the health care setting, or in the community.”

The country’s tally on reported COVID-19 cases soar to 63,001 cases which put several major hospitals in the “danger zone” as critical care units reach maximum capacity.

On Friday, July 17, the Department of Health reported 1,841 new infections, of which 710 were “fresh” or detected in the last three days and 1,131 were part of the department’s validation backlog.

The City of Manila tallied the most new cases with 441 more infections, followed by Quezon City with 140, Mandaluyong with 96, Cebu City with 87 and Navotas with 85 infections.


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