Air pollution is dangerous to human health. It can cause many diseases, especially in the breathing passage. The particle with size less than 10 microns is concerned to be respirable. These particles may be some chemicals toxic to our body, and if the density is large, they will be very harmful. Generally, people will feel uncomfortable if the density of respirtable particles is over 150mg/m3. This experiment provides a model of pollution detector based on UVA scattering. Since some dust particles may be as small as 0.05 micron or below, the strong wavelength dependence of the Rayleigh scattering (~λ^-4) makes UV being a more favorable choice than visible light as the light source in this application if very tiny particles are involved in the polluted air sample.

The aim of this research project is to design an air pollution monitoring system using ultraviolet light (UV) detectors and UV source. Mr Lee Wai Tong modified the setup done by Mr. Li Bin's. Several new structural changes have been made so as to improve the sensitivity and portability of the monitoring system This system has been demonstrated during Outreach Day 2006 and 2007. It has been added as a demo kit for the Mini-lecture series and used during school visits.