Hydrating the respiratory tract: An alternative explanation why masks lower severity of COVID-19
"It is important to note that our measurements were carried out in the absence of air leakage around the mask edges. For non-N95 masks, such leakage is often significant and will proportionately lower both their ability to filter pathogens and the effective humidity increase of inspired air. So, in practice the cotton mask humidification efficiency will drop somewhat to values comparable with the tight-fitting N95 mask. The surgical and polyester-cotton blend masks, which also will be subject to leakage, then are expected to perform somewhat lower than the N95 and all-cotton masks. These considerations imply that for day-to-day use, a tight-fitting N95 (or KN95) mask is preferred, whereas after infection while quarantined, a cotton mask may be more beneficial to the wearer, provided no others at risk of infection share space with the infectee."