Trish Greenhalgh, professor of primary care at the University of Oxford, says Covid-19 "is most commonly transmitted by droplets emitted when we cough, sneeze, shout, sing and even just breathe in close proximity to others". “Cloth face coverings are highly effective at blocking droplets coming out of the mouth and nose. They’re not perfect, but if you can stop 90% or 95% of the droplets this will cause a very dramatic reduction in the number of people who catch the virus. “Face coverings, which can be made out of a double layer of cloth, are a crucially important measure for bringing the country out of lockdown, since in reality few of us can get properly back to work without getting within two metres of other people (either while travelling to work or in offices and factories). “We can’t stay behind our front doors forever, and nobody wants a second wave of Covid-19, so covering our faces will become the new normal in public places, workplaces and on public transport."