UC Berkeley

Residences are important sites of daily bioaerosol exposure; yet the relative contributions of outdoor and indoor sources are not well-understood. Biological particles can be detected using laser-induced fluorescence. Applying real-time instrumentation, this work investigated the contributions of indoor and outdoor sources to fluorescent aerosol particle exposures in a northern California residence with three human residents and a dog. Time- and size-resolved total and fluorescent particle concentrations were measured indoors and outdoors, using an ultraviolet aerodynamic particle sizer (UVAPS) and a switching valve. Time-resolved occupancy status and household activities, such as cooking and cleaning, were obtained using occupant-maintained logs and wireless electronic sensors. Our observations show the indoor to outdoor ratio of fluorescent particles is strongly influenced by occupancy, and that indoor sources contribute a considerable fraction of total daily fluorescent particle exposures at home. This work will improve understanding of the relationship between human activities and bioaerosol exposure in residences.