Why does rain increase the concentrations of environmental bioaerosols during monsoon?

Abstract

Rain has been known to remove aerosol particles from the atmosphere; however, it was recently discovered that rain events during monsoon increase the concentrations of culturable bioaerosols in ground-level air environments. To explain this phenomenon, several hypotheses were tested via bioaerosol measurement experiments in this study. The experimental measurements with limited variations of environmental conditions revealed that the phenomenon of the effect of rain on bioaerosols might be caused by the transportation of bioaerosols by falling raindrops from higher altitude to the ground, where the bioaerosols accumulate, as well as by the decrease in UV irradiation intensity during rain events. We studied the effects of several environmental parameters on bioaerosol concentrations.