A B S T R A C TWe studied the effects of human activity on concentrations of fungal and bacterial bioaerosols in indoor air environments. We conducted measurement experiments for concentrations of bioaerosols and aerosol particles in test chambers with people performing various activities inside. We found that the number of people and human activities had positive correlations with the concentrations of bacterial bioaerosols. However, the concentration of fungal bioaerosols was not influenced by human presence or activities. The findings regarding the concentrations of fungal and bacterial bioaerosols and the effects of human presence and activities will be useful for studying control methods against bioaerosols.

a b s t r a c tRain has been known to remove aerosol particles in air environments. The aerosol particles were captured and removed from the air by rain and the concentration of aerosol particles significantly decreased after rain events. Therefore, rain is regarded as having a good effect on air environments in terms of the respiratory health of the general public. However, humid environments produced by long-term rain events such a monsoon may be a sufficient condition for the growth of microorganisms and vibrations because of the splashing of droplets may facilitate the aerosolization of ground microorganisms. We therefore hypothesize that the rain may increase concentrations of bioaerosols in outdoor air environments, thereby possibly influencing respiratory diseases.To verify this hypothesis, at the initial stepwise approach, we measured the concentration of airborne biological particles before, after, and during rain in a monsoon season. The measurement data of the concentration of fungal particles and bacterial particles show quantitatively that the bioaerosol concentrations during the rain event are several times higher than the concentration of the bioaerosols in the condition of no rain.