Question: what apparatus would you use for measuring oxygen levels to decide if a room needs better vetilation?

Louise Wood answered on 23 Jun 2021:

You use a handheld meter, which is similar to the size of a typical touch screen phone (just a bit thicker). It has a small display screen and some buttons. If you google “Crowcon Oxygen Personal Gas monitor Oxygen”. That should show you an orange device that is similar.

Air is made up of lots of gases such as Nitrogen, carbon dioxide, argon, water vapour, Ozone and Oxygen (as well as tiny amounts of other gases). Oxygen is the important one and the one we mainly read. For example, you have too many people in a poorly ventilated room then Carbon dioxide and heat radiating out of the bodies builds up. This can make the room stuffy and people feel sleepy.

What we do is we will wave the oxygen monitor around in the air, particularly around the corners of the rooms or behind screens where the flow tends to not mix with the general workplace air, these are points where oxygen can lower and CO2 can increase. We are looking to read 21% Oxygen content but the legal permitted amount is +/- 1% so we have to read between 20.79 and 21.21. If we are reading outside this, then we know there is a problem and we have to do something and introduce air into the room.