Diffusion tubes
Diffusive samplers or ‘diffusion tubes’ are widely used for indicative monitoring of ambient nitrogen dioxide (NO2) concentrations. Diffusion tubes are particularly useful:
- when simple, indicative techniques will suffice;
- to give an indication of longer-term average NO2 concentrations;
- for indicative comparison with the Air Quality Strategy Objectives based on the annual mean;
- for highlighting areas of high NO2 concentration; and
- where installation of an automatic analyser is not feasible.
They are useful for identifying areas of high NO2 concentration, particularly when dealing with sources such as traffic emissions, which do not change much from day to day.
These tubes are mounted on lamp posts or buildings to give pollution readings over a four week period. Babergh uses this method to measure levels of NO2 at a number of locations throughout the district.
Pollution measurements from previous years can be found in the Council's Air Quality Reports, together with an interpretation of the results. |