Simulating in-vehicle exposure : field and modeling based assessment -

Abstract

This study examines ambient contaminant infiltration to in-vehicle microenvironments to assess in-vehicle exposure and potential self-pollution from vehicular exhaust. For this purpose, in and out-vehicle CO and PM₂.₅ concentrations were monitored in several cars under idle and moving conditions using common ventilation modes. Field measurements were coupled with mathematical modeling to define air exchange rates (AER), PM₂.₅ deposition rates (DR), and equivalent emission rates (ER) representing potential self-pollution. Using CO as an indicator, the AER ranged between 1.8 and 112.2 h⁻¹ and generally increased with vehicle speed under all tested ventilation modes. The DR of PM₂.₅ ranged between 0.6 and 12.6 h⁻¹ and was also dependent of speed and ventilation conditions. Self-pollution varied widely with car make, speed and ventilation mode with corresponding average equivalent ERs of 2.86 to 238.3 mg-h for CO and 0.01 to 2.5 mg-h for PM₂.₅