Simultaneous light scattering and intrinsic fluorescence measurement for bioaerosol detection

Several workers have reported the development of systems which allow the measurement of intrinsic fluorescence from particles irradiated with ultra-violet radiation; see for example, Hairston et al (1997); Seaver et al. (1999); Yong-le Pan et al. (1999). The fluorescence data are frequently recorded in conjunction with other parameters such as particle size, measured either as a function of optical scatter or as an aerodynamic size. The motivation for this work has been principally the detection of bioaerosols within an ambient environment. Previous work by the authors has shown that an analysis of the scattering profile of a particle, i.e. : the spatial distribution of light scattered by the particle carried in a sample air-stream, can provide an effective means of particle characterisation and classification in terms of both size and shape parameters (Hirst and Kaye, 1996; Kaye, 1998). Current work is aimed at the simultaneous recoding of both spatial scattering and fluorescence data from individual particles with a view to substantially enhanced discrimination of biological aerosols.