title: Chamber bioaerosol study: human emissions of size-resolved fluorescent biological aerosol particles.
abstract: Humans are a prominent source of airborne biological particles in occupied indoor spaces, but few studies have quantified human bioaerosol emissions. The chamber investigation reported here employs a fluorescence-based technique to evaluate bioaerosols with high temporal and particle size resolution. In a 75-m(3) chamber, occupant emission rates of coarse (2.5-10 μm) fluorescent biological aerosol particles (FBAPs) under seated, simulated office-work conditions averaged 0.9 ± 0.3 million particles per person-h. Walking was associated with a 5-6× increase in the emission rate. During both walking and sitting, 60-70% or more of emissions originated from the floor. The increase in emissions during walking (vs. while sitting) was mainly attributable to release of particles from the floor; the associated increased vigor of upper body movements also contributed. Clothing, or its frictional interaction with human skin, was demonstrated to be a source of coarse particles, and especially of the highly fluorescent fraction. Emission rates of FBAPs previously reported for lecture classes were well bounded by the experimental results obtained in this chamber study. In both settings, the size distribution of occupant FBAP emissions had a dominant mode in the 3-5 μm diameter range.
authors.affiliation: Department of Civil and Environmental Engineering, University of California, Berkeley, CA, USA.
authors.forename: S
authors.initials: S
authors.lastname: Bhangar
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA.
authors.forename: R I
authors.initials: RI
authors.lastname: Adams
authors.affiliation: Center for the Built Environment, University of California, Berkeley, CA, USA.
authors.forename: W
authors.initials: W
authors.lastname: Pasut
authors.affiliation: Department of Chemistry and Biochemistry, University of Denver, Denver, CO, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Huffman
authors.affiliation: Center for the Built Environment, University of California, Berkeley, CA, USA.
authors.forename: E A
authors.initials: EA
authors.lastname: Arens
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Taylor
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA.
authors.forename: T D
authors.initials: TD
authors.lastname: Bruns
authors.affiliation: Department of Civil and Environmental Engineering, University of California, Berkeley, CA, USA.
authors.forename: W W
authors.identifier: http://orcid.org/0000-0001-5645-3357
authors.initials: WW
authors.lastname: Nazaroff
mesh_terms: D000336:Aerosols / Q000032:analysis*; D016902:Air Pollution, Indoor / Q000032:analysis*; D004784:Environmental Monitoring; D006801:Humans; D010316:Particle Size
chemical_list: D000336:Aerosols
keywords: Flooring; Human activity; Occupancy; Resuspension; Source strength; UV-APS