Multiple-anode PMT makes possible the detection, discrimination, enrichment, and deposition of bioaerosols on-the-fly

Environmental and occupational monitoring of hazardous aerosols, especially bioterrorism threats by way of dispersal of pathogenic bioaerosols, requires advanced systems that can identify harmful bioaerosol particles in quasi real-time and in situ. Instruments presently available to identify airborne biowarfare agents (BWA), mostly based on biochemical technologies, cannot be run continuously and are generally costly in both time and logistical burden. In these instruments, aerosol particles are collected and pretreated first, and then analyzed and identified. There is always a big challenge to get rid of the overwhelmingly dominant background aerosol particles in the pretreating process; a large quantity of background aerosol particles could contaminate the reactions, and disable the biochemical assay within minutes. A different approach, based on the analysis of UV laser-induced fluorescence spectra (UV-LIF), has resulted in instruments that can continually and rapidly discriminate bio-threat-like aerosols from many kinds of ambient aerosols. However, this approach struggles with specific identification and produces high false alarm rates, especially in instruments that rely on only two or three fluorescence bands. To overcome the limitations of each approach, a combined method has been devised, in which the dispersed spectroscopy of the UV-LIF signal is used as a first-stage discriminator to prescreen the background aerosol particles and rapidly get rid of interfering aerosols, while specific biochemical technology is used to identify suspect aerosols with high accuracy for bioaerosol detection and characterization.