World Health Organization (WHO) advice says non-medical face coverings should be worn in public where social distancing is not possible. Coronavirus is spread when droplets are sprayed into the air when infected people talk, cough or sneeze. Those droplets can then fall on surfaces. The WHO says there is also emerging evidence of airborne transmission of the virus, with tiny particles hanging in aerosol form in the air. cloth face coverings and masks can help reduce the spread from people who are contagious but have no symptoms or are yet to develop symptoms. This is called asymptomatic or presymptomatic transmission.