The Centers for Disease Control and Prevention on Friday clarified its stance on various kinds of masks, acknowledging that the cloth masks frequently worn by Americans do not offer as much protection as surgical masks or respirators.
While this disparity is widely known to the general public, the update marks the first time the C.D.C. has explicitly addressed the differences. The agency’s website also no longer refers to a shortage of respirators.
The change comes as infections with the highly contagious Omicron variant continue to soar. Some experts have said that cloth masks are inadequate to protect from the variant, and have urged the C.D.C. to recommend respirators for ordinary citizens.
Most blue surgical face masks used by many during the pandemic are not enough to avoid people from being infected with COVID-19, an alarming new study has found.
Airborne simulation experiments showed that cotton masks, surgical masks, and N95 masks provide some protection from the transmission of infective SARS-CoV-2 droplets/aerosols; however, medical masks (surgical masks and even N95 masks) could not completely block the transmission of virus droplets/aerosols even when sealed.
We noticed that speaking through some masks (particularly the neck gaiter) seemed to disperse the largest droplets into a multitude of smaller droplets (see fig. S5), which explains the apparent increase in droplet count relative to no mask in that case. Considering that smaller particles are airborne longer than large droplets (larger droplets sink faster), the use of such a mask might be counterproductive. Furthermore, the performance of the valved N95 mask is likely affected by the exhalation valve, which opens for strong outwards airflow. While the valve does not compromise the protection of the wearer, it can decrease the protection of persons surrounding the wearer. In comparison, the performance of the fitted, non-valved N95 mask was far superior.