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New studies on health effects of traffic-related pollution

February 2018

HEI will fund three studies in a new research program aimed at assessing adverse health effects from exposure to traffic-related air pollution. The program’s request for applications (RFA 17-1), issued in January 2017, solicited studies that would consider such health effects and disentangle them from spatially correlated confounding or modifying factors — most notably, traffic noise, socioeconomic status (SES), and the built environment, including green space.

The response to the RFA was strong: HEI received 51 preliminary applications. The HEI Research Committee then invited 11 full applications. These were reviewed and scored by an ad hoc panel of experts, after which the Research Committee reviewed and discussed the top-ranked ones. Important criteria in deciding which studies to recommend for funding were the novelty of the approach, responsiveness to objectives of the RFA, the overall design, and the likelihood that the study will accomplish its proposed aims.

The studies recommended by the Research Committee were approved by the Board of Directors. They are described below.

Meredith Franklin, an assistant professor at the University of Southern California, and her colleagues will build on the Children’s Health Study (CHS) in Southern California (the subject of a previous HEI study led by Frank Gilliland; see HEI Research Report 190). The goal of the study is to evaluate the adverse effects of non-tailpipe emissions and of noise on children’s respiratory health. They will make use of “Cohort E,” which is the most recent CHS cohort, with children ages 5–15 recruited from 2002 to 2012, and with longitudinal data on asthma and lung function. They will develop a new exposure model for non-tailpipe PM metals using compositional data from existing PM filters at 200 locations in 8 CHS communities, along with data on intersections, freeway on/off ramps, and road slopes. They will use a dispersion model to estimate exposure to tailpipe emissions. For noise, they will use the Federal Highway Traffic Noise Model. In addition, they plan to assess several other factors, such as SES, green space, genetic ancestry, and stress.

Payam Dadvand, assistant professor, and Jordi Sunyer, professor, both at the Barcelona Institute for Global Health (ISGlobal, previously CREAL), Spain, and colleagues will set up a new cohort of healthy pregnant women in Barcelona, Spain, from 2018 to 2020. They will assess birth weight, fetal growth trajectories, and placental function for each pregnancy. Exposure to traffic-related air pollution will be estimated using hybrid models, including land-use regression and dispersion models for various pollutants. In addition, personal measurements for NO2 as well as home outdoor measurements for NO2, PM2.5, and traffic noise will be obtained. Data on time–activity patterns will be collected and used in combination with exposure measurements to estimate dose of inhaled pollutants. The statistical analyses will aim at disentangling the roles of noise and socioeconomic status, and will include metrics for green space, physical activity, diet, and stress.

Ole Raaschou-Nielsen, a professor at the Danish Cancer Society Research Center in Copenhagen, Denmark, and colleagues will evaluate effects of traffic-related air pollution and other factors on myocardial infarction, stroke, diabetes, and related biomarkers in Denmark. They will make use of various cohorts, including an administrative cohort covering the entire Danish population in the period 1993–2018. They will assess traffic-related air pollution using the AirGIS dispersion model for pollutants, including PM10, PM2.5, NO2, black carbon, and ultrafine particles, which can help distinguish different sources. In addition, they will assess noise using the Nordic Prediction Method, which incorporates detailed information about street and building geometry, among many other features. They plan to assess numerous other factors, including SES, stress, and comorbidities.

These studies are expected to start in spring 2018 and be completed within four years. The investigators have been invited to present posters at the 2018 HEI Annual Conference in Chicago with details of their study plans.