Inhalation intake of ambient air pollution in California's South Coast Air Basin

Abstract

Reliable estimates of inhalation intake of air pollution and its distribution among a specified population are important for environmental epidemiology, health risk assessment, urban planning, and environmental policy. We computed distributional characteristics of the inhalation intake of five pollutants for a group of $25,000 people ($29,000 persondays) living in California's South Coast Air Basin. Our approach incorporates four main inputs: temporally resolved information about people's location (latitude and longitude), microenvironment, and activity level; temporally and spatially explicit model determinations of ambient concentrations; stochastically determined microenvironmental adjustment factors relating the exposure concentration to the ambient concentration; and, age-, gender-, and activityspecific breathing rates. Our study is restricted to pollutants of outdoor origin, i.e. it does not incorporate intake in a microenvironment from direct emissions into that microenvironment. Median estimated inhalation intake rates (mg d À1 ) are 53 for benzene, 5.1 for 1,3-butadiene, 8.7 Â 10 À4 for hexavalent chromium in fine particulate matter (Cr-PM 2.5 ), 30 for diesel fine particulate matter (DPM 2.5 ), and 68 for ozone. For the four primary pollutants studied, estimated median intake rates are higher for non-whites and for individuals in low-income households than for the population as a whole. For ozone, a secondary pollutant, the reverse is true. Accounting for microenvironmental adjustment factors, population mobility and temporal correlations between pollutant concentrations and breathing rates affects the estimated inhalation intake by 40% on average. The approach presented here could be extended to quantify the impact on intakes and intake distributions of proposed changes in emissions, air quality, and urban infrastructure. r

Modeling population exposures to outdoor sources of hazardous air pollutants

“…These findings confirm some of the recent results on the important role of commuting and human activities in influencing population exposures to benzene and other motor-vehiclerelated pollutants Marshall et al, 2006). Our analysis extends these results to many other gaseous and particulate HAPs and examines this issue further through a nationwide analyses by each of the five different emissions HAPs source category.…”

Do the health benefits of cycling outweigh the risks?

“…Driving or cycling in traffic may result in air pollution exposures that are substantially higher than overall urban background concentrations (Kaur et al 2007). Consequently, even relatively short times spent in traffic may contribute significantly to daily exposures (Beckx et al 2009a(Beckx et al , 2009bFruin et al 2004;Marshall et al 2006;Van Roosbroeck et al 2007). Table 1 summarizes studies that specifically compared exposures during car driving and cycling within the same study.…”

Evaluating the application of multipollutant exposure metrics in air pollution health studies

“…Intake fractions also use emission information, and have primarily been used as an indicator of exposure to a specific source. Intake fractions have been used for primary (Lobscheid et al, 2012;Marshall et al, 2005) and secondary pollutants (Greco et al, 2007;Levy et al, 2003); inhalation and other intake pathways such as ingestion (Bennett et al, 2002a); and for varied sources such as motor vehicles (Marshall et al, 2006), power plants (Levy et al, 2003), and dry cleaners (Evans et al, 2000).…”