Center for Clean Air Research

Project Title: Effects of long-term exposure to traffic-derived particles and gases on subclinical measures of cardiovascular disease in a multi-ethnic cohort

Investigators: Joel D. Kaufman (Project PI), Sverre Vedal, Timothy Larson, Michael Yost, Adam Szpiro, Paul Sampson, Lianne Sheppard

Institution: University of Washington, Seattle, WA

Objectives

Exposure to air pollution, especially particulate matter (PM), is consistently linked to cardiovascular disease (CVD) in epidemiological studies. Larger effects of long-term PM exposure are seen with improved exposure estimates. Traffic is a major source of air pollution and an important contributor to CVD; integrating refined traffic exposures into an epidemiologic study of air pollution and CVD would be an important advance. The primary objective of this project is to estimate the effect of individual-level exposure to traffic-derived air pollution on measures of CVD in the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air) using novel exposure estimation methods and incorporating on-road, in-transit exposure estimates.

Approach

This project has three tasks. First, a multi-pollutant exposure prediction model for roadway-associated air pollution will be built that incorporates complex spatial information on primary and secondary traffic-derived particles and gases. This model will yield: 1) city-wide exposure surfaces for traffic-derived air pollution components for four study cities, and 2) distributions of traffic-derived air pollutant estimates for various roadway types and traffic conditions in each city. Second, individual-level exposure estimates will be developed for traffic-derived air pollutants, utilizing the models built under the first objective. We will enhance and validate these estimates using a personal, residential, and in-vehicle monitoring campaign, including real-time data logged GPS tracking, in a subset of 144 MESA Air participants. Third, the effect of individual-level exposure to traffic-related air pollution, including on-roadway exposures, on longitudinal vascular outcomes (including left ventricular mass and retinal arteriolar diameter) and DNA methylation will be estimated in a cohort of over 4,000 MESA Air participants.

Expected results

This project will transform MESA Air from its current focus on PM2.5 into a multi-pollutant study that can meaningfully investigate the impact of traffic-derived air pollution on cardiovascular health using a source-to-exposure approach. We will integrate data on traffic-derived pollutants from the novel, state-of-the-art mobile monitoring campaign (Project 1) into a multi-pollutant exposure model that incorporates participant-specific time-location information. The relationship between traffic exposure and change in measures of CVD will be assessed in a large and well-characterized cohort, making this project the first application of a multi-pollutant approach to a large-scale air pollution epidemiology study. Results will, in turn, assist policymakers in taking a multipollutant approach to controlling adverse health impacts of air pollution exposure.

Supplemental Keywords: epidemiology, volatile organic compounds, atherosclerosis