Car emissions account for half of the carbon monoxide pollution in the United States, one third of the nitrogen oxide pollution, and 10% of fine particulate matter emissions. Areas of heavy traffic congestion — which see concentrated emissions levels in the ambient air — are of particular concern, as previous research has linked such pollution with negative effects on fetal health.

A 2011 study by Columbia University published in the American Economic Journal: Applied Economics, “Traffic Congestion and Infant Health: Evidence from E-ZPass,” compared fetal health outcomes for mothers living near congested and uncongested toll plazas on three major highways in Pennsylvania and New Jersey. The researchers focused on areas where toll plazas had instituted E-ZPass, an electronic toll collection system that allows cars to travel through more efficiently and thereby diminishes congestion and pollution. The study drew its conclusions by looking at the health outcomes of nearly 30,000 births among mothers who lived within two kilometers of an E-ZPass toll plaza.

The study’s key findings are:

• In areas where E-ZPass was adopted, rates of infant prematurity decreased by between 6.7% and 9.1%; this means that, out of the sample studied, 255 preterm births were avoided.
• Introduction of E-ZPass was correlated with a reduction in the incidence of low birth weight by between 8.5% and 11.3%; that means 275 cases of low birth weight were avoided.
• Other variables such as changes in the characteristics of mothers living in the vicinity and shifts in nearby housing prices were checked and eliminated as possible alternate explanations for the changes in fetal health outcomes.

The researchers state that their findings “suggest that the adoption of E-ZPass was associated with significant improvements of infant health.” Given that some 1 million infants annually may be negatively affected by traffic-related pollution, the authors note, the issue of congestion has significant public health and economic implications.

More information on the issue can be found in a related study in Environmental Health Perspectives,  “Ambient Air Pollution and Risk of Congenital Anomalies: A Systematic Review and Meta-analysis.”

Tags: cars, children, congestion, fossil fuels, infrastructure, pollution