The fear of flying at Mount 50KThe researchers, from the University of Cambridge and Imperial College London in the UK, noted that when speaking, we exhale smaller droplets, or aerosols, which spread easily around a room, and accumulate if ventilation is not adequate.In contrast, coughing expels more large droplets, which are more likely to settle on surfaces after they are emitted, they said.Scientists agree that the vast majority of COVID-19 cases are spread through indoor transmission, whether via aerosols or droplets.The researchers noted that it only takes a matter of seconds for aerosols to spread over two meters when masks are not worn, implying that physical distancing in the absence of ventilation is not sufficient to provide.