Chromatic modulation monitoring of airborne particulates

Given the wide ranging concern about air pollution by particulates of sizes 2 to 10 µm, there is a need for a cost-effective, easily deployed, portable system of moderate accuracy (rather than high precision) for temporary use on sites or on board vehicles to monitor such particulate concentrations. This paper describes such a system, which is based upon a chromatic modulation technique. A brief explanation of the chromatic approach is given followed by a description of the particulate monitoring unit. The performance of this unit has been established via various calibration tests and the instrument has been deployed for real life use at a number of sites. Some preliminary results are presented from a city centre bus terminus, the depot of a major bus operator and a site close to an official monitoring station.