title: Toward refined estimates of ambient PM2.5exposure: Evaluation of a physical outdoor-to-indoor transport model.
abstract: Because people spend the majority of their time indoors, the variable efficiency with which ambient PM2.5penetrates and persists indoors is a source of error in epidemiologic studies that use PM2.5concentrations measured at central-site monitors as surrogates for ambient PM2.5exposure. To reduce this error, practical methods to model indoor concentrations of ambient PM2.5are needed. Toward this goal, we evaluated and refined an outdoor-to-indoor transport model using measured indoor and outdoor PM2.5species concentrations and air exchange rates from the Relationships of Indoor, Outdoor, and Personal Air Study. Herein, we present model evaluation results, discuss what data are most critical to prediction of residential exposures at the individual-subject and populations levels, and make recommendations for the application of the model in epidemiologic studies. This paper demonstrates that not accounting for certain human activities (air conditioning and heating use, opening windows) leads to bias in predicted residential PM2.5exposures at the individual-subject level, but not the population level. The analyses presented also provide quantitative evidence that shifts in the gas-particle partitioning of ambient organics with outdoor-to-indoor transport contribute significantly to variability in indoor ambient organic carbon concentrations and suggest that methods to account for these shifts will further improve the accuracy of outdoor-to-indoor transport models.
authors: Department of Environmental Sciences, Rutgers University, 14 College Farm Rd., New Brunswick, NJ 08901, USA.
authors: Natasha
authors: N
authors: Hodas
authors: School of Public Health, Rutgers University, 683 Hoes Lane West, Piscataway, NJ 08854, USA ; Environmental and Occupational Health Sciences Institute, 170 Frelinghuysen Rd., Piscataway, NJ 08854, USA.
authors: Qingyu
authors: Q
authors: Meng
authors: Atmospheric Sciences, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors: Melissa M
authors: MM
authors: Lunden
authors: Department of Environmental Sciences, Rutgers University, 14 College Farm Rd., New Brunswick, NJ 08901, USA ; Environmental and Occupational Health Sciences Institute, 170 Frelinghuysen Rd., Piscataway, NJ 08854, USA.
authors: Barbara J
authors: BJ
authors: Turpin
keywords: Aerosol Penetration and Persistence (APP) model; Outdoor and Personal Air (RIOPA) study; PM2.5 exposure; Relationships of Indoor; gas-particle partitioning; organic aerosol