As well as measuring the room, think about the number of occupants and decide how much noise you’re willing to accept. Noisy air filters often get turned off. Models with extras such as ionisers are not recommended as they can release toxic chemicals into the air.

Here is a guide from the joint U.K. teaching unions on how to conduct an air audit for the classroom (can also be applied in any room). Teachers please please do not underestimate the impact you can have on your students health by following this guide. neu.org.uk/sites/defaul...