LAUSR

The determinants of thetemporal variability of indoordust concentrationsof semivolatileorganiccompounds(SVOCs)remains mostly unexplored. We examined temporalvariability ofdust concentrations and factors affecting dust concentrations for a wide range of SVOCs.We collected dust samples three times from29 California homes during a period of 22monthsand quantified concentrations of 47 SVOCs in 87 dust samples. We computed intraclass correlation coefficients (ICCs) using three samples collected within the same house.We calculated correlation coefficients (r) between two seasons with similar climate (spring and fall)and between two seasons with oppositeclimate (summer and winter).Among 26 compounds that were detected in more than 50% of the samples at all three visits, 20 compounds had ICCs above 0.50 and 6 compounds had ICCs below 0.50. For 19out of 26 compounds, correlation coefficients between spring and fall (r = 0.48-0.98) were higher than those between summer and winter (r = 0.09-0.92), implying seasonal effects on dust concentrations.Our study showed that within-home temporal variability of dust concentrations was small(ICC > 0.50) for most SVOCs, but dust concentrations may vary over time for some SVOCswith seasonal variations in source rates, such as product use.