Researchers have modelled indoor airborne virus transmission via aerosols, which are tiny droplets ejected from people's mouths when they exhale, speak, or cough. According to the yet-to-be peer-reviewed study, published in the preprint server arXiv, when an infected person does this, the virus particles hitch a ride on the aerosols as they land on nearby surfaces, or are inhaled by another person. Based on their experiments, the researchers found that in indoor spaces, good ventilation will filter some of the virus out of the air, but may leave more viral particles on surfaces. In the classroom setting, after running a 50-minute simulation with an asymptomatic teacher consistently talking, only 10 per cent of the aerosols were filtered out, the scientists said. The majority of the particles were instead deposited on the walls, they added.