Impact of temperature on the dust/gas partitioning of semi-volatile organic compounds in indoor environments

Semi-volatile organic compounds (SVOCs) are one of the ubiquitous families of indoor air pollutants. They can be found in the gas phase as well as in the adsorbed/absorbed phases including airborne particles and settled dust. The dust/gas partition coefficient, Kd, is the ratio of the SVOC concentrations in the settled dust and the gas phase at the equilibrium state thus is a key parameter for modeling the indoor transport and partitioning of SVOCs. Studies have shown that the value of Kd depends on the temperature, the organic fraction in dust, the dust size and density, etc. For indoor SVOC modeling in the context of climate change, the temperature effect on Kd should be addressed particularly. In the present study, a linear relationship between Log10 Kd and the inverse of temperature was derived for 18 SVOCs including polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). Kd decreases by 91.8 to 99.6% when the temperature rises from 10 to 40 °C. The influence of temperature on Kd and the indoor concentration was estimated for three SVOCs using a validated mechanistic model. The dust phase concentration of the three SVOCs may vary by 1.5 orders of magnitude due to variations in Kd in a temperature range between 10 and 30 °C.