Comparison of short-term variations (15-minute averages) in outdoor and indoor PM2.5 concentrations.
Measurements of 15-min average PM2.5 concentrations were made with a real-time light-scattering instrument at both outdoor (central monitoring sites in three communities) and indoor (residential) locations over two seasons in the Minneapolis-St. Paul metropolitan area. These data are used to examine within-day variability of PM2.5 concentrations indoors and outdoors, as well as matched indoor-to-outdoor (I/O) ratios. Concurrent gravimetric measurements of 24-hr average PM2.5 concentrations were also obtained as a way to compare real-time measures with this more traditional metric. Results indicate that (1) within-day variability for both indoor and outdoor 15-min average PM2.5 concentrations was substantial and comparable in magnitude to day-to-day variability for 24-hr average concentrations; (2) some residences exhibited substantial variability in indoor aerosol characteristics from one day to the next; (3) peak values for indoor short-term (15-min) average PM2.5 concentrations routinely exceeded 24-hr average outdoor values by factors of 3-4; and (4) relatively strong correlations existed between indoor and outdoor PM2.5 concentrations for both 24-hr and 15-min averages.
Division of Environmental and Occupational Health, School of Public Health, University of Minnesota, Minneapolis, USA.
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G
Ramachandran
J L
JL
Adgate
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N
Hill
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Sexton
G C
GC
Pratt
D
D
Bock
D000203:Activities of Daily Living; D000336:Aerosols; D016902:Air Pollution, Indoor / Q000032:analysis*; D004781:Environmental Exposure; D004784:Environmental Monitoring / Q000379:methods; D006798:Housing; D006801:Humans; D010316:Particle Size; D015203:Reproducibility of Results; D012621:Seasons; D013997:Time Factors
D000336:Aerosols