The World Health Organisation changed its guidance in July to acknowledge the possibility of aerosol transmission, such as during choir practice, or when in restaurants or fitness classes. Microscopic droplets ejected while speaking evaporate to leave behind aerosol particles big enough to carry viable virus, the paper showed. An increase of about 35 decibels in loudness, or the difference between whispering and shouting, boosts the particle emission rate by 50 times. "Not all indoor environments are equal in terms of aerosol transmission risk," said lead researcher William Ristenpart. The global death toll from the virus passed 900,000 on Wednesday, as worldwide cases topped 27.7 million, a Reuters tally.

Source: Otago Daily Times September 10, 2020 08:37 UTC