Liquid particles from the airways can be divided into two categories depending on their size – droplets and aerosols – although the division is fluid. While droplets fall to the ground after a short distance, aerosols can remain airborne for extended periods of time and spread or accumulate indoors, especially in confined and poorly ventilated indoor spaces. They are emitted when people breathe and talk, particularly when they’re laughing, shouting or singing, or in situations with increased breathing.
The coronavirus generally spreads via droplets and aerosols during close, protracted contact with an infected person. Close contact makes transmission easier because there can be higher concentrations of the virus. Beyond a distance of 1.5 metres, droplets generally sink to the ground and aerosols become diluted in the air of the room. This means the virus is less concentrated, which reduces the risk of transmission – which generally happens as it gets more diluted in the room if it is well ventilated.
You can find out how to protect yourself and others, and how important it is to properly ventilate a room, on the page Protect yourself and others.
You’ll find more information on the different ways the coronavirus is transmitted on the page Disease, Symptoms, Treatment.