Face masks may not protect against coronavirus in rain, say WHO and PHE

Face masks are less effective in preventing the spread of coronavirus when worn in rain, according to Public Health England (PHE) and the World Health Organization (WHO).

Following heavy downpours across much of the UK, and with winter just around the corner, the health authorities are warning that face coverings must be replaced if they became damp - a message that has been echoed by many experts.

Tim Spector, a professor of genetic epidemiology at King’s College London, is calling on Downing Street officials to provide the public with “clear advice” on the issue.

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“Masks need to be changed regularly and this is particularly important to understand in damp and wet weather,” he told The Times.

In France, where wearing a face mask outdoors is compulsory in some cities, “local guidelines encourage users to carry a second mask because of the risk”, says the newspaper.

Leading cardiologist Aseem Malhotra has also criticised the UK government for failing to launch a “public campaign to make people aware that [rain] can make their masks ineffective”, adding that “it is obvious that masks will get damp as people shop and travel in bad weather”.

Current guidance from the Department of Health and Social Care advises members of the public to “change the face covering if it becomes damp or if you’ve touched it”.

The WHO advises that face masks should consist of at least three layers of different material, but states that moisture can undermine this protection.

“For any type of mask, appropriate use and disposal are essential to ensure that they are as effective as possible and to avoid any increase in transmission,” the UN health agency says.

“All masks should be changed if wet or visibly soiled. A wet mask should not be worn for an extended period of time. Replace masks as soon as they become damp with a new clean, dry mask.”

The warnings come as Storm Alex continues to wreak havoc in the UK, with flood alerts still in place across much of the country following heavy rain, high winds and power cuts.