SO HOW VIRUS PROOF IS YOUR MASK?
Using lab conditions, a professor answers the burning question
FACE coverings may be compulsory in more places now than ever — but how much protection do they really afford to people around you?
‘A face covering should help minimise the spread of micro-organisms (including the Covid-19 virus) by the wearer,’ says Val Edwards- Jones, an emeritus professor of medical microbiology at Manchester Metropolitan University.
‘During coughing, talking or sneezing, tiny droplets that may contain the virus are expelled from the mouth and will be absorbed into the mask fabric, rather than being transmitted to others.’
But which is the best design to choose? ‘The World Health Organisation (WHO) has advised wearing triple-layer face coverings,’ says Professor Edwards- Jones. ‘ But not all masks conform to WHO recommendations.’
We asked Professor Edwards- Jones, who has developed her own range of masks ( everycloudsp. com), to test various types, ranging from cheap, disposable ones to more fashionable versions, to see the extent to which they prevented droplets from getting into the air.
While wearing each mask, she coughed into a series of Petri dishes which were holding a medium in which bacteria can flourish.
‘While viruses can be up to 1,000 times smaller than bacteria, this gives us a good indication of how effective each mask might be at preventing transmission,’ she says. ‘It is difficult to test how “virus-proof” a mask is because viruses require a live host and can’t be cultured on a Petri dish. But we all have bacteria in our mouths. When we cough, some escape. If one passes through a mask and lands on a Petri dish, it can grow, giving us an indication of how permeable that mask is.’
As a control, she placed a dish in front of her mouth and coughed on it three times, before repeating the process with different dishes for each mask. The dishes were incubated for 48 hours, then the number of ‘colonies’ — groups of bacteria — was counted. The number of colonies on the dish coughed on without a mask was 65.
While all masks reduced the number of bacteria passed into the air, some blocked them fully while others allowed almost 80 per cent through.
So which masks were most effective?
NB: Apart from the KN95, none of the masks reviewed here claims to be medical-grade.