We monitor air quality using 2 methods, as described below:
Diffusion tubes
These are simple passive samplers where the contaminant to be monitored is absorbed onto a metal disc held in the top of the tube which is coated in a specific absorber, over an extended period of exposure and subsequently analysed at a laboratory.
We use this method of monitoring to measure nitrogen dioxide and have some results dating back to 1995. Diffusion tubes have the advantage of being relatively inexpensive however the monthly results have to be calculated into an annual mean to ensure accurate results. We also undertake co-location studies at the continuous units to improve the reliability of the data.
Continuous monitoring units
These continuously monitor nitrogen dioxide and particulates - PM10 - and also meteorological data.
We bought 2 units in January 1999, one static unit which is located at The Forest School, Winnersh and a mobile unit, which has been located at various locations around the Borough. This used to be moved every 6 months but is now situated on a permaent basis within the Air Quality Management Area, at Woodward Close where the Reading Road underpasses the M4 motorway.
Using the data from these units, comparisons can be made with both the hourly mean and annual mean objectives for nitrogen dioxide and with the 24 hourly mean and the annual mean objectives for PM10.
