Continuous Bioaerosol Monitoring Using UV Excitation Fluorescence: Outdoor Test Results

Abstract

This report describes procedures and results of recent outdoor tests in evaluating a prototype sin- gle particle fluorescence analyzer (SPFA), an instrument that is being developed to simultaneously monitor am- bient concentrations of both biological and nonbiologi- cal aerosols using optical techniques. Recent modifica- tions to the SPFA are also noted and discussed. During recent outdoor tests, aerosols were generated contain- ing four different types of biological material: ova albu- min, MS-2 phage, Erwinia herbicola vegetative cells and Bacillus subtilis spores. Analysis of the SPFA results in- dicates that a probability of detection of at least 87% was achieved for target aerosol concentrations as low as a few (1-5) particles/liter. Moreover, comparison with dif- ferent reference instruments indicate that the SPFA can achieve absolute quantitative detection efficiencies for individual biological aerosols of at least 70% (assuming appropriate alignment and threshold settings are made). During some of the outdoor tests different nonbiological aerosols were also released that generally did not gener- ate any significant fluorescent signals. Although official test scores have not yet been distributed, we provide here the SPFA results for each of the aerosol releases made during the test. Analysis of the relative fluorescent inten- sities in the visible and UV spectral bands suggests that these data can be used in the future to provide an indi- cation of the type of biological aerosol being released as well. C c ∞ 2001 John Wiley & Sons, Inc.⁄This article is a US Government work and, as such, is in the public domain in the United States of America. and monitor human pathogens or other hazardous biological materials as aerosols. Our research project has focused on using optical techniques to sample and monitor ambient air on a continuous basis, in order to provide essentially a real-time analysis of the biological aerosol concentration.