Distinguishing Biotic and Abiotic Particles Using an Ultraviolet Aerodynamic Particle Sizer for Real-Time Detection of Bacterial Bioaerosols

Abstract

Exposure to airborne biological particles, termed bioaerosols, can have adverse effects on human health, such as infectious diseases, acute toxic reactions, and allergies. The search for ways of preventing and curing the harmful effects of bioaerosols has created a strong demand for the study and development of efficient methods of monitoring and controlling them. The ultraviolet aerodynamic particle sizer (UVAPS) system is a promising monitoring device for the real-time detection of airborne microorganisms. Fundamentally, it is an airborne particle counter and spectrometer capable of measuring the fluorescence emitted by living microorganisms measuring 0.5-15 mu m. Fluorescence sensitivity of a UVAPS is influenced significantly by the settings of the pulsed UV laser and the photomultiplier tube detector. To measure bioaerosols more precisely using the UVAPS system, the fluorescence baseline should be checked occasionally using nonfluorescent test particles, such as polystyrene latex (PSL) particles. In this research, we demonstrate the adjustment process for obtaining optimized UVAPS fluorescence sensitivity to distinguish between viable particles related to microorganisms and nonviable environmental particles. Using the optimized UVAPS fluorescence settings, the aerosol and fluorescence characteristics of various particles, including viable microorganisms (e.g., Escherichia coli, Bacillus subtilis, and Staphylococcus epidermidis) and nonviable aerosols (e.g., NaCl, multiwall carbon nanotubes, PSL, and fluorescent PSL), can be determined. In addition, the biological culturability of the sampled bacterial particles is compared with their fluorescence percentage measured by the UVAPS.