Comparison of short-term variations (15-minute averages) in outdoor and indoor PM2.5 concentrations

Gurumurthy Ramachandran, John L. Adgate, Nicholas Hill, Ken Sexton, Gregory C. Pratt, Donald Bock

Research output: Contribution to journalArticlepeer-review

77 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)1157-1166
Number of pages10
JournalJournal of the Air and Waste Management Association
Issue number7
StatePublished - Jul 2000
Externally publishedYes

ASJC Scopus subject areas

  • Waste Management and Disposal
  • Management, Monitoring, Policy and Law


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