'Alarming' Variations: Is Your Mask Safe? 

A health alert has been issued over some reusable facemasks with evidence that some filter out just 7per cent of harmful bacteria.

The warning comes from consumer experts at Which? after a survey of 15 masks which suggest some offer little or no protection.

Three of the masks, available online and in the high street, were so flimsy that they have been issued with a ‘Don’t Buy’ rating.