A valved mask decreases the work of breathing (on expiration) for those who labor in dusty environments, but the facilitated exit of expired air runs counter to the need to protect others during the pandemic.
Also worth noting that the "KN95" designation does NOT mean that this is an "N95" mask with optimal filtering. The KN is a manufacturer's name for the product, designed to be deceptive to buyers.
A valved (true N95) *IS* appropriate protection for the wearer against CV.
ReplyDeleteIt does not, however, protect society. You wear the N95 for yourself, and your wear the homemade mask to protect everyone else. I personally wear both if I am in the store, and only the homemade mask if I am in an isolated outdoor space.
While a surgical mask may be effective in blocking splashes and large-particle droplets, a face mask, by design, does not filter or block very small particles in the air that may be transmitted by coughs, sneezes, or certain medical procedures. Surgical masks also do not provide complete protection from germs and other contaminants because of the loose fit between the surface of the mask and your face.
ReplyDeletehttps://www.fda.gov/medical-devices/personal-protective-equipment-infection-control/n95-respirators-surgical-masks-and-face-masks
https://tools.niehs.nih.gov//wetp/public/hasl_get_blob.cfm?ID=3178
ReplyDeleteCONCLUSIONS Two types of N95 half-mask respirators and 2 types of surgical masks were challenged with aerosolized MS2 virus. The experiments were carried out following a manikin-based protocol. The results indicate that N95-certified respirators may not necessarily provide a proper protection against virus,