By Rachel Garrod
The wearing of masks during this COVID-19 pandemic still seems highly contentious. A number of issues influence our compliance with mask wearing: ideology, knowledge and, of course, cultural norms. Japan and other Asian nations have habitually worn masks for many years, particularly when travelling on public transport. But, for us Europeans, the wearing of masks is associated with a loss of freedom. How can we respond normally with one another when we can´t see our facial expressions? Really, do they do any good? Are we all just being muzzled!
Well, we are many months into this pandemic now and evidence that was not available at the start is now emerging. One of the early pieces of observational evidence came in June when two hair stylists who both wore surgical masks during work were diagnosed as having COVID-19. Although they passed the virus onto family members, the vast majority of their clients were free from it.
As the pandemic continues we have been able to acquire more rigorous evidence. A review study from August (Leffler et al) found that weekly increases in mortality were four times lower in places where mask wearing was the norm or mandated by the government. It is, of course, difficult to separate the effect of masks from other preventative measures such as social distancing and hand washing. However, with animal studies we can more easily control these variables. Researchers from Hong Kong recently conducted a study on hamsters infected with COVID-19, using a mask barrier between cages as the proxy for mask wearing. Only about 25 per cent of the animals became infected when the mask barrier was in place as opposed to two-thirds of the animals without a barrier.
Some people tell me they are concerned about a build-up of carbon dioxide or a loss of oxygen with the wearing of masks. This will only occur if the mask is air-tight, which clearly a cloth covering/surgical mask is not. Oxygen enters the lungs as a result of pressure changes between the exterior and the interior of the thoracic cavity. A mask does not affect this pressure variable, nor does it stop us exhaling carbon dioxide. Some people with breathing problems may be exempt as masks can certainly exacerbate feelings of breathlessness – albeit without a drop in oxygen levels.
On the whole it seems that masks do not so much prevent you from inhaling droplets as limit your expulsion of particles. There are even early suggestions that wearing a mask may reduce the viral load received and that in turn may reduce the severity of infection. With as many as 80 per cent of people now thought to be asymptomatic (contagious but without symptoms) this makes the wearing of masks even more important. So, you wearing a mask protects others and in turn they protect you. But this only works if we all wear one!
Rachel Garrod (Ph.D. Physiotherapist) specialises in physiotherapy for older
people with chronic respiratory disease and other chronic illnesses.
Tel. (+34) 699 501 190