Facemasks with valves are half useless

If you’re wearing a face mask with a little plastic valve embedded in it, you should know that valves compromise the effectiveness of the mask—and this is true whether your mask is a hardware-store N95 or a designer cloth mask.

Example of another N95 face mask with valve.

In the age of COVID-19, we wear masks when out and about for two reasons: First, we hope they might protect us from other people, at least a little bit. 

The second reason is more significant: they protect us from infecting others if it turns out we are infected and don’t know it.

Valves defeat that second purpose. A valved mask is letting your breath out unfiltered; the valve acts as a little escape hatch for any virus-laden droplets you’re breathing out. Some municipalities that require masks have specified that masks with valves do not count. You also won’t typically see valved masks in healthcare settings for the same reason. As the CDC explains:

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.

If you have a stash of N95s that you previously used as dust masks, or if you’re considering buying a designer cloth mask that has a valve (somehow the fancy ones all seem to have valves), be aware that they only filter your inhaled air, not your exhaled air. And right now, that’s not good enough.

Example of N95 like mask style with valve

As the saying goes, “your mask protects me, my mask protects you,” so please use a valve-less mask to do your part in reducing transmission.

Here are examples of face mask with valves that do NOT protect anybody else except the wearer:

Example of textiles mask with valve

Please avoid this type of masks.