Coronavirus: Surgical face masks will not protect you from the virus

Wearing a surgical face mask is of little use to protect you from the coronavirus and could actually be more problematic, an engineer has warned.

The rush to buy face masks and respirators as the Covid-19 pandemic spread may have lulled people into a false sense of security.

Engineer Marc Anthony Azzopardi from the University of Malta explains the risks associated with masks if used wrongly.

Surgical masks

A surgical face mask is designed to limit the amount of droplet spray emitted from a surgeon’s mouth and nose to avoid contaminating the surgical field.

These masks protect the patient from the surgeon, and not the surgeon from the patient.

The mask material has pores many times larger than a virus and is not tight fitting to the face. Hence, these masks are not very effective at protecting the wearer from very fine dust, or virus laden droplets.

They are however effective at preventing one from touching the nose and face with possibly contaminated hands.

Respirators are face masks with specialised filters: these are more effective but it is inadvisable to reuse them and cleaning the filter with alcohol will damage them

Respirators

These are masks that have filters. These respirators are “electrical devices” that work using the electrostatic attraction.

Respirators are a completely different kettle of fish. They are much better fitting to the face and are meant to make a seal. They need to be fit tested and should be used together with other personal protective equipment (PPE), particularly eyewear for maximum effectiveness.

These masks attract and then trap the tiniest of particles inside their non-woven electret polypropylene filters.

Electret materials retain a semi-permanent electrical charge within them. As long as this electrical charge persists inside the material, very small particles are reliably lodged within the mask. This is what gives these respirators the prized 95% (or higher) filtration efficiency.

Contamination

Both face masks and respirators may become contaminated after use and must not be touched. If touched, the hands must then be washed immediately and thoroughly.

Removal and disposal also has to be performed very carefully, lest these masks and respirators may become themselves a source of infection.

Reuse is inadvisable

In times of shortages the temptation arises for reusing such disposable masks and respirators more than once. Since these could have been contaminated, reuse is highly inadvisable. Research suggests that it may take many hours, possibly several days for viable virus concentrations to drop sufficiently to make used masks safe to handle or reuse.

Washing respirator kills it

Washing a high-performance respirator with alcohol, water, detergent, or bleach damages these respirators irreversibly, by discharging the electret that makes them work. Autoclaving and other forms of heating also damages them.

An experimental technique involving intense short-wavelength, germicidal ultraviolet radiation shows promise for sterilisation with minimal mask damage, and has been researched by several groups around the world. This is currently being evaluated at the University of Malta to mitigate the severe shortages of high-performance respirators, particularly for medical professionals.

The information in this article was compiled by Dr Ing. Marc Anthony Azzopardi, a lecturer with the Department of Electronic Systems Engineering, and distributed by the Univeristy of Malta.