What Dave Mole has reminded us is that the emphasis on masks has changed over time. Comments were initially about the increased risks to the wearer which Dr Harries stated very clearly. This was lot to do with masks getting dirty when the emphasis was on preventing infection from dirty surfaces. Events have now moved on to reducing increased risks to non infected public from an asymptomatic carrier due to breath-bourne transmission. This tips the balance from non-wearing to wearing as formal advice.