Continuous bioaerosol monitoring using UV excitation fluorescence: Outdoortest results

This report describes procedures and results of recent outdoor tests in eva luating a prototype single particle fluorescence analyzer (SPFA), an instru ment that is being developed to simultaneously monitor ambient concentratio ns of both biological and nonbiological aerosols using optical techniques. Recent modifications to the SPFA are also noted and discussed. During recen t outdoor tests, aerosols were generated containing four different types of biological material: ova albumin, MS-2 phage, Erwinia herbicola vegetative cells and Bacillus subtilis spores. Analysis of the SPFA results indicates that a probability of detection of at least 87% was achieved for target ae rosol concentrations as low as a few (1-5) particles/liter. Moreover, compa rison with different reference instruments indicate that the SPFA can achie ve absolute quantitative detection efficiencies for individual biological a erosols of at least 70% (assuming appropriate alignment and threshold setti ngs are made). During some of the outdoor tests different nonbiological aer osols were also released that generally did not generate any significant fl uorescent signals. Although official test scores have not yet been distribu ted, we provide here the SPFA results for each of the aerosol releases made during the test. Analysis of the relative fluorescent intensities in the v isible and UV spectral bands suggests that these data can be used in the fu ture to provide an indication of the type of biological aerosol being relea sed as well. (C) 2001 John Wiley & Sons, Inc.