title: Emission rates and the personal cloud effect associated with particle release from the perihuman environment.
abstract: Inhalation exposure to elevated particulate matter levels is correlated with deleterious health and well-being outcomes. Despite growing evidence that identifies humans as sources of coarse airborne particles, the extent to which personal exposures are influenced by particle releases near occupants is unknown. In a controlled chamber, we monitored airborne total particle levels with high temporal and particle-size resolution for a range of simulated occupant activities. We also sampled directly from the subject's breathing zone to characterize exposures. A material-balance model showed that a sitting occupant released 8 million particles/h in the diameter range 1-10 μm. Elevated emissions were associated with increased intensity of upper body movements and with walking. Emissions were correlated with exposure, but not linearly. The personal PM10exposure increment above the room-average levels was 1.6-13 μg/m3during sitting, owing to spatial heterogeneity of particulate matter concentrations, a feature that was absent during walking. The personal cloud was more discernible among larger particles, as would be expected for shedding from skin and clothing. Manipulating papers and clothing fabric was a strong source of airborne particles. An increase in personal exposure was observed owing to particle mass exchange associated with a second room occupant.
authors.affiliation: Department of Civil and Environmental Engineering, University of California, Berkeley, CA, USA.
authors.forename: D
authors.initials: D
authors.lastname: Licina
authors.affiliation: Department of Civil and Environmental Engineering, University of California, Berkeley, CA, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Tian
authors.affiliation: Department of Civil and Environmental Engineering, University of California, Berkeley, CA, USA.
authors.forename: W W
authors.identifier: 0000-0001-5645-3357
authors.initials: WW
authors.lastname: Nazaroff
mesh_terms: D000328:Adult; D000336:Aerosols / Q000032:analysis*; D000393:Air Pollutants / Q000032:analysis; D016902:Air Pollution, Indoor / Q000032:analysis; D003020:Clothing; D003198:Computer Simulation; D004781:Environmental Exposure / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods; D005260:Female; D006801:Humans; D019570:Inhalation Exposure / Q000032:analysis*; D008297:Male; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D012119:Respiration; D057185:Sedentary Behavior; D016138:Walking
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D052638:Particulate Matter
keywords: activity type; cross-contamination; human emissions; particle sources; particle-size distribution; personal exposure