A gas mask is a breathing device that filters air so the wearer can breathe safely in dangerous conditions. It can also protect against disease-causing bacteria and viruses.
A variety of respirator designs are available, but all require proper fit-testing and training. People with lung diseases, elderly people or those with claustrophobia may have difficulty using a mask. Some people cannot wear a mask or hooded respirator at all. A mask does not protect against certain types of cancer or infections in the blood.
Some studies suggest that wearing a mask increases carbon dioxide and pH levels, increases cardiovascular stress and decreases cognitive performance during exercise, but does not appear to cause other hemodynamic, metabolic or subjective effects.13 It is important to note that self-report complaints of discomfort during mask use,9 respiratory fatigue,15 and headache16 may be related to a slightly elevated carbon dioxide concentration. These symptoms are not a result of the mask itself, but rather a physiological response to increased oxygen demand by the muscles in the face and head area.
SARS-CoV-2 is transmitted primarily by inhalation of virus-laden respiratory droplets produced when a person coughs, sneezes, talks or breathes. The main community benefit of masking for SARS-CoV-2 control is the reduction of the emission of these droplets by the mask wearer (“source control”), and to prevent inhalation of them by others (50% of transmissions).1