Particle size distribution and composition in a mechanically ventilated school building during air pollution episodes.
Parker-JL; Larson-RR; Eskelson-E; Wood-EM; Veranth-JM
Indoor Air 2008 Oct; 18(5):386-393
Particle count-based size distribution and PM(2.5) mass were monitored inside and outside an elementary school in Salt Lake City (UT, USA) during the winter atmospheric inversion season. The site is influenced by urban traffic and the airshed is subject to periods of high PM(2.5) concentration that is mainly submicron ammonium and nitrate. The school building has mechanical ventilation with filtration and variable-volume makeup air. Comparison of the indoor and outdoor particle size distribution on the five cleanest and five most polluted school days during the study showed that the ambient submicron particulate matter (PM) penetrated the building, but indoor concentrations were about one-eighth of outdoor levels. The indoor:outdoor PM(2.5) mass ratio averaged 0.12 and particle number ratio for sizes smaller than 1 microm averaged 0.13. The indoor submicron particle count and indoor PM(2.5) mass increased slightly during pollution episodes but remained well below outdoor levels. When the building was occupied the indoor coarse particle count was much higher than ambient levels. These results contribute to understanding the relationship between ambient monitoring station data and the actual human exposure inside institutional buildings. The study confirms that staying inside a mechanically ventilated building reduces exposure to outdoor submicron particles. PRACTICAL IMPLICATIONS: This study supports the premise that remaining inside buildings during particulate matter (PM) pollution episodes reduces exposure to submicron PM. New data on a mechanically ventilated institutional building supplements similar studies made in residences.
Particle-aerodynamics; Particle-counters; Particulate-sampling-methods; Particulates; Air-filters; Air-quality-control; Air-quality-measurement; Airborne-particles; Pollutants; Exposure-assessment; Exposure-levels; Indoor-air-pollution; Indoor-environmental-quality;
Author Keywords: Indoor air quality; Ambient aerosol; Submicron particles; PM2.5; Coarse particulate matter; Children; Grimm 1.108 aerosol spectrometer; Speciated composition
John M. Veranth, University of Utah, Rocky Mountain Center for Occupational & Environmental Health, Pharmacology and Toxicology, 30 South 2000 East, Salt Lake City, UT 84112-5820
University of Utah, Salt Lake City, Utah