Impacts of Vehicle Emission Regulations and Local Congestion Policies on Birth Outcomes Associated with Traffic Air Pollution.

introductionIn the United States, billions of dollars have been spent implementing interventions to reduce traffic-related air pollution (TRAP). These interventions are usually regulatory actions focused on reducing tailpipe emissions. However, they also include local programs to reduce traffic congestion and excess vehicle emissions, such as electronic tolls and roadway capacity improvements. Few health studies have empirically evaluated the direct impact of air pollution exposure reductions from these emission regulations and congestion reduction programs; no studies have examined infant health, an important population health outcome linked to air pollution exposures.

objectiveAssess changes in birth outcomes for all recorded births in Texas from 1996 to 2016 associated with (1) long-term cumulative regulatory improvements of motor vehicle emissions and resulting TRAP change and (2) local congestion reduction programs that may yield localized TRAP changes over shorter time periods.

methodsWe used Vital Statistics data in Texas from 1996 to 2016 (n = 8.1 million recorded births; n = 6,158,518 births analyzed after exclusions). We calculated diverse traffic-related exposure measures using residential addresses at the time of delivery. We implemented research triangulation methods using different study design and analysis approaches to test our primary hypotheses on the effects of long-term cumulative regulatory improvements and local congestion reduction programs on birth outcomes.

resultsTraffic-related exposure measures (nitrogen dioxide [NO

conclusionsTRAP is an important environmental health and justice issue that affects pregnancy. Our results provide some evidence supporting that cleaning up the vehicle fleet was more impactful at decreasing adverse pregnancy outcomes than local programs aimed at reducing congestion.