title: The impact of mass transfer limitations on size distributions of particle associated SVOCs in outdoor and indoor environments.
abstract: Semi-volatile organic compounds (SVOCs) partition between the gas phase and airborne particles. The size distribution of particle-associated SVOCs impacts their fate in outdoor and indoor environments, as well as human exposure to these compounds and subsequent health risks. Allen et al. (1996) previously proposed that the rate of mass transfer can impact polycyclic aromatic hydrocarbon (PAH) partitioning among different sized particles, especially for time scales relevant to urban aerosols. The present study quantitatively builds on this idea, presenting a model that incorporates dynamic SVOC/particle interaction and applying this model to typical outdoor and indoor scenarios. The model indicates that the impact of mass transfer limitations on the size distribution of a particle-associated SVOC can be evaluated by the ratio of the time to achieve gas-particle equilibrium relative to the residence time of particles. The higher this ratio, the greater the influence of mass transfer limitations on the size distribution of particle-associated SVOCs. The influence of such constraints is largest on the fraction of particle-associated SVOCs in the coarse mode (>2 μm). Predictions from the model have been found to be in reasonable agreement with size distributions measured for PAHs at roadside and suburban locations in Japan. The model also quantitatively explains shifts in the size distributions of particle associated SVOCs compared to those for particle mass, and the manner in which these shifts vary with temperature and an SVOC's molecular weight.
authors.affiliation: Department of Building Science, Tsinghua University, Beijing, China.
authors.forename: Cong
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Building Science, Tsinghua University, Beijing, China.
authors.forename: Yinping
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Building Science, Tsinghua University, Beijing, China; Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, NJ, USA; International Center for Indoor Environment and Energy, Technical University of Denmark, Lyngby, Denmark. Electronic address: weschlch@rwjms.rutgers.edu.
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Weschler
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D016902:Air Pollution, Indoor / Q000032:analysis*; D004784:Environmental Monitoring; D007564:Japan; D010316:Particle Size; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis; D055549:Volatile Organic Compounds / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D011084:Polycyclic Aromatic Hydrocarbons; D055549:Volatile Organic Compounds
keywords: Airborne particles; Exposure; Gas/particle partitioning; Kinetic limitations; Partitioning dynamics; Phthalates