Protecting against Covid‐19 aerosols

Protecting against Covid-19 aerosols THE value of masks has been debated throughout the Covid-19 pandemic. There seems little doubt that the dispersion of coronavirus droplets is reduced when people with Covid-19 wear masks or face coverings. What has been more unclear is whether masks, of which there are many types, will protect wearers against inhalation of the virus. Recent research at Cambridge University Hospitals NHS Foundation Trust has shown that the quality of masks that healthcare workers wear makes a huge difference to their risk of coronavirus infection. The research showed that wearing a high-grade mask known as an FFP3 (also called a respirator) can provide 100 per cent protection whereas there is a far greater chance of staff becoming infected if they wear a surgical mask. These results are not surprising since experiments performed more than 50 years ago at the Animal Virus Research Institute, now The Pirbright Institute, showed that only a very small amount of protection was provided by surgical or industrial masks, and none by paper masks, against the inhalation of virus associated with large airborne particles (>6 microns in diameter). Based on those results it was proposed that ‘the only effective method of protection would be provided by respirators capable of trapping large and small particles’. This and the Cambridge data suggest wearing an FFP3 mask is advisable in any scenario where there is a risk of inhaling aerosols of coronavirus, particularly in poorly ventilated areas.