New study looks at impact of emissions reductions on birth outcomes

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HEI has published a new Research Report, Impacts of Vehicle Emission Regulations and Local Congestion Policies on Birth Outcomes Associated with Traffic Air Pollution. The study presented in the report, led by Perry Hystad of Oregon State University, examined whether reductions in traffic-related air pollution were associated with improved birth outcomes in Texas from 1996 to 2016. In particular, the report focused on long-term cumulative effects of national regulations to reduce vehicle emissions and shorter-term effects of local actions to reduce traffic congestion.

The investigators found consistent associations between estimated exposure to traffic-related air pollution and adverse birth outcomes throughout the 20-year study period, but the magnitude of those associations decreased over time, parallelling air quality improvements. Here are key findings from the report:

• The team estimated that annual nitrogen dioxide exposures decreased by more than 50% for pregnant individuals over the course of the study period, while total vehicle miles traveled decreased by just over 9%. Measures of traffic congestion did not change significantly after toll implementation or roadway improvement projects.
• The study found consistent associations between estimated exposure to traffic-related air pollution and adverse birth outcomes throughout the 20-year study period, but the magnitude of those associations decreased over time, parallelling air quality improvements. Local toll implementation and roadway improvement projects did not meaningfully change associations between congestion measures and adverse birth outcomes.
• The study provides some evidence that the cumulative effects of long-term regulations aimed at reducing tailpipe emissions have been more effective at decreasing adverse birth outcomes than shorter-term localized programs aimed at reducing congestion.

Read the report