Question: What does a diffusion tube do?

Sarah Naylor answered on 16 Mar 2018:

A diffusion tube is a small see through plastic tube, approximately 7cm long which has a colour cap on one end which contains two steel mesh grids. These grids are soaked in an solution called TEA solution which absorbs nitrogen dioxide. The tubes are left open in the air (usually attached to lampposts) for a month before they are sent to a laboratory for analysis. The lab determines how much nitrogen dioxide is in the TEA solution. This then gives us a concentration of the nitrogen dioxide from the air in that location over that month. We can use these results to see whether there is too much nitrogen dioxide in the air at that location.