Predicting the gas-phase concentration of semi-volatile organic compounds from airborne particles: Application to a French nationwide survey

Semi-volatile organic compounds (SVOCs) partition indoors between the gas phase, airborne particles, settled dust, and other surfaces. Unknown concentrations of SVOCs in the gas phase (C-g) can be predicted from their measured concentrations in airborne particles. In previous studies, the prediction of C-g depended largely on choosing a specific equation for the calculation of the particle/gas partition coefficient. Moreover, the prediction of C-g is frequently performed at a reference temperature rather than the real indoor temperature. In this paper, a probabilistic approach based on Monte Carlo simulation was developed to predict the distribution of SVOCs' C-g from their concentrations in airborne particles at the target indoor temperature. Moreover, the distribution of the particle/gas partition coefficient of each SVOC at the target temperature was used. The approach was validated using two measured datasets in the literature: the predicted C-g from concentrations measured in airborne particles and the measured C-g were generally of the same order of magnitude. The distributions of the C-g of 66 SVOCs in the French housing stock were then predicted. The SVOCs with the highest median C-g, ranging from 1 ng/m(3) to >100 ng/m(3), included 8 phthalates (DEP, DiBP, DBP, DEHP, BBP, DMP, DiNP, and DMEP), 4 polycyclic aromatic hydrocarbons (fluorene, phenanthrene, fluoranthene, and anthracene), 2 alkylphenols (4-tert-butylphenol and 4-tert-octylphenol), 2 synthetic musks (galaxolide and tonalide), tributyl phosphate, and heptachlor. The nationwide, representative, predicted C-g values of SVOCs are frequently of the same order of magnitude in Europe and North America, whereas these C-g values in Chinese and Indian dwellings and the C-g of polybrominated diphenyl ethers in U.S. dwellings are generally higher. (C) 2016 Elsevier B.V. All rights reserved.