Variability of Personal Exposure to Fine Particulates for Urban Commuters inside Automobiles

Over the past decade, a growing body of evidence has emerged to suggest a causal link between short-duration exposure to elevated levels of fine airborne particulate matter and adverse health consequences. It is believed that much of this peak exposure occurs in transport microenvironments both because of the higher levels of fine particulates associated with road traffic, primarily from diesel exhaust emissions, and because of the significant amount of time people spend traveling (for instance, 80 min/day for residents of Sydney, Australia). Although previous studies have suggested substantial differences in exposure rates because of factors such as choice of mode, route, in-vehicle conditions, and meteorological factors, current measurement techniques have restricted insights to fairly coarse sampling intervals (e.g., every hour and every trip). As a consequence, little tangible evidence is available on how pollution varies over a trip and, most critically, about the location, duration, and magnitude of peak excursions within trips. With these issues in mind, this current paper reports on a study in which capabilities of Global Positioning Systems and real-time particle monitors are combined to address the problem for an urban commute in Sydney. This ability to reference pollution data precisely and spatially, and to identify hot spots in particular, holds considerable promise for both understanding and reporting of such data in the future.