Face mask vs. face shield: is one more effective than the other?
The lack of conclusive evidence regarding the effectiveness of face masks in protecting against Covid-19 as well as their difficult manageability have made some people turn to face shields instead. Although research suggests these can be helpful, the fact that face shields are not tight fitting makes that they do not protect against aerosols – the micro droplets that have probably caused the large numbers of infections during mass indoor events earlier this year.
One of the most surprising aspects of the Covid-19 crisis is the lack of conclusive evidence about the effectiveness of face covering to prevent the spread of the virus. The CDC - Centers for Disease Control and Prevention - is quite clear: masks are most likely to reduce the spread of Covid-19 when they are widely used by people in public settings. The CDC thus supports the position that the virus spreads mainly among people who are in close contact with each other. From this perspective, masks are seen as a simple barrier to help prevent respiratory droplets from travelling when people cough, sneeze or talk.
Other bodies, such as the Dutch National Institute for Public Health, take a different position. Adherence to the basic rules of staying home, getting tested in case symptoms arise, staying 1,5 metres apart and avoiding crowds is thought to be much more important. The Institute feels the academic literature does not offer clear consensus about the effect of non-medical face masks and warns that the quality of the materials, the fit on the face and the way the user wears it are key factors in the effectiveness of non-medical masks.
Possibly as a result of the inconclusive evidence concerning face masks and their difficult manageability, some people have turned to face shields instead. Face shields consist of a film made from plastic or other transparent material and is attached to a band that goes around the top of your head. The face shield appears to gain popularity in places where face covering is compulsory in public places, such as the Australian state of Victoria. Although the state’s Department of Health recommends a face mask over face shields, going so far as to state that any paper or textile covering qualifies as a face mask, some people prefer the face shield because of its obvious advantages: they create less irritation to the face and allow for a more normal form of communication.
In relation to face shields, experts note that aerosols may still enter and exit as face shields are not tight fitting. The role of aerosols – the tiny droplets that stay in the air for extended periods of time – in spreading the virus during mass indoor events has been well-known since the beginning of the pandemic. The little academic research that exists on face shields also stresses the role of aerosols, while stressing that “much is not understood about [their] behaviour […] and the risk they pose”. Although it does not help ordinary citizens in making a choice for or against face shields, the preliminary conclusion for health care workers is that “face shields provide a useful adjunct to respiratory protection for workers caring for patients with respiratory infections. However, they cannot be used as a substitute for respiratory protection when it is needed”.