The amount of respiratory virus in the air can build up in poorly ventilated areas. This increases the risk of spreading COVID-19 and other respiratory infections, especially if many infected people are present. The virus can also remain in the air after an infected person has left.

Meeting outdoors greatly reduces this risk, but this may not always be possible.

Bringing fresh air into a room by opening a door or a window, even for a few minutes at a time, helps remove older stale air that could contain virus particles and reduces the chance of spreading infections. Trickle vents (small vents usually on the top of a window) or grilles can also be useful for bringing a little fresh air constantly. The fresher air that is brought inside, the quicker any viruses will be removed from the room.

Ventilation is most important if someone in your household has COVID-19 or another respiratory virus, to try and stop the virus from spreading. See further guidance here.

Good ventilation has also been linked to health benefits such as better sleep and fewer sick days off from work or school.

There is further advice on what you can do to improve ventilation.