The Observation and Characterisation of Fluorescent Bioaerosols Using Real-Time UV-LIF Spectrometry in Hong Kong from June to November 2018

Hong Kong is an area of complex topography, with mixtures of urban and greenbelt spaces. Local bioaerosol concentrations are multifaceted, depending on seasonal variations of meteorological conditions and emission sources. This study is the first known attempt at both quantitatively measuring and identifying airborne bioaerosol contributions by utilising multiple single particle ultraviolet light induced fluorescence spectrometers. Based at the Hong Kong University of Science and Technology’s super-site, aWIBS-NEO and PLAIR Rapid-E were operated from June to November, 2018. The purpose of this long-term campaign was to observe the shift in wind patterns and meteorological conditions as the seasons change, and to investigate how, or if, this impacts on the dispersion and concentrations of bioaerosols in the area. Bioaerosol concentrations based on particle auto-fluorescence spectra remained low through the summer and autumn months, averaging 4.2 L-1 between June and October. Concentrations were greatest in October, peaking up to 23 L-1. We argue these concentrations are dominated by dry-weather fungal spores, as evidenced by their spectral profile and relationship with meteorological variables. We discuss potential bioaerosol source regions based on wind sector cluster analysis and believe this study paints a picture of bioaerosol emissions in an important region of the world.