Wearing a face mask is one of the medically accepted ways to protect us from COVID-19. And because we’re required to wear a mask in the “new normal,” people have been finding other types of masks that are more comfortable to wear. Which most likely led to the wide use of N95 respirators with exhalation valve.
What makes this N95 special?
The Centers for Disease Control and Prevention (CDC) explains that the presence of the valve “reduces exhalation resistance,” making it easier for the wearer to exhale. Also, some users feel that a respirator with an exhalation valve keeps the face cooler and reduces moisture build up inside the facepiece.
However, a Twitter post by the San Francisco Department of Public Health raised an alarm on the safety of N95 masks with valves. “Still seeing a lot of these masks out there, it's confusing, because they are called N95- but the ones with the **valves** or openings on the front are NOT safe, and may actually propel your germs further!!” the post reads.
What do the experts say about this?
A study on “Respiratory Performance Offered by N95 Respirators and Surgical Masks” published by the National Library of Medicine shows that the “N95 filtering facepiece respirators may not achieve the expected protection level against bacteria and viruses. An exhalation valve on the N95 respirator does not affect the respiratory protection; it appears to be an appropriate alternative to reduce the breathing resistance.”
CDC also notes that respirators with exhalation valves are not recommended 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.
3M, one of the well-known manufacturers of face masks, echoes this information in a recently issued technical bulletin. “The purpose of a respirator’s exhalation valve is to reduce the breathing resistance during exhalation; it does not impact a respirator’s ability to provide respiratory protection. The valve is designed to open during exhalation to allow exhaled air to exit the respirator and then close tightly during inhalation, so inhaled air is not permitted to enter the respirator through the valve.”
It further clarifies, “While a valve does not change a respirator’s ability to help reduce a wearer’s exposure to bioaerosols (airborne particles originating from biological sources such as animals, plants, fungi, bacteria, protozoa, and viruses), a person who is exhibiting symptoms of illness should not wear a valved respirator, because exhaled particles may leave the respirator via the valve and enter the surrounding environment, potentially exposing other people.”
It is important to note that in recent studies, CDC says a significant portion of individuals with coronavirus lack symptoms (“asymptomatic”) and that even those who eventually develop symptoms (“pre-symptomatic”) can transmit the virus to others before showing symptoms. This means that the virus can spread between people interacting in close proximity—for example, speaking, coughing, or sneezing—even if those people are not exhibiting symptoms.
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CDC maintains its recommendations to wear cloth face coverings—not N95 respirators, as these are critical supplies that must continue to be reserved for healthcare workers and other medical first responders—in public settings where other social distancing measures are difficult to maintain (e.g., grocery stores and pharmacies) especially in areas of significant community-based transmission.
The six-feet social distancing is also highly emphasized by CDC in slowing the spread of the virus. “Cloth face coverings fashioned from household items or made at home from common materials at low cost can be used as an additional, voluntary public health measure,” notes CDC.
What are the appropriate uses of valve masks? According to 3M, their valve mask called the N95 particulate respirator is ideally suited for hot/dusty work settings that require long periods of wear. The respirator is designed for use for particles such as those from grinding, sanding, sweeping, sawing, bagging, or other dusty operations. This respirator can also help reduce inhalation exposures to certain airborne biological particles (e.g. mold, Bacillus anthracis, Mycobacterium tuberculosis), but cannot eliminate the risk of contracting infection, illness, or disease.