Can Cutting Traffic Congestion Help Prevent Premature Births?

12.21.2102 | As you blast through the E-ZPass tollbooths this holiday travel season on our way to friends and family, you can be thankful not only that the little electronic eye makes the trip a little faster–no more fumbling for that dropped quarter, no more inching forward in an unending line– but also for its role in helping kids stay healthier.

A new study finds that among roughly 30,000 births within 2 kilometers of a toll plaza in a recent study, 255 premature births and 275 low birth weigh births were averted because of the installation of an E-ZPass.

Traffic congestion has many harms– pollution, expense, quality of life. But it has one harm that is rarely discussed. Child health.

EZ-Pass reduces the number of idling cars, and with it, noxious emissions.The E-ZPass system, for example, has been shown to reduce nitrogen oxide by 11% and hydrocarbons and carbon monoxide by 40% owing to reduced lines, stop-and-go traffic, and congestion. Another study found carbon monoxide and nitrogen oxide truck emissions were cut by 23% and 6%, respectively.

Janet Currie and Reed Walker, in “Air Pollution and Infant Health: A Lesson from New Jersey” show that reducing these pollutants also leads to healthier pregnancies, and healthier babies. Among families living within 2 kilometers of expressway toll booths, premature births fell by between 6.7% and 16% after the installation of E-ZPass tolling systems. In addition to a decline in premature births, the incidence of low birth weight fell by between 8.5% and 11.3%.

What’s particularly convincing about this study is that the researchers used a very rigorous method to isolate cause and effect, moving beyond simple correlations, which can leave the question hanging, which comes first, the chicken or the egg? Women living close to busy roadways, for example, where pollution is an issue, are more likely to have other characteristics tied to poor pregnancy outcomes, such as lower income, less education, higher probability of being a teen mother. This is in part because wealthier people are more likely to be able to move away from pollution. So is it these characteristics or the pollution that is causing more difficult pregnancies?

It is difficult to design a study that takes all of these confounding and interrelated factors into account. Currie and Reed sidestepped this issue by creating a “natural experiment” similar to drug trials with a control and experimental group. Currie and Reed took advantage of a policy change that funded the installation of E-ZPass lanes in Pennsylvania and New Jersey to compare the birth outcomes among women who lived near the new E-ZPass toll booths with mothers who lived along an equally busy highway but without a toll booth. The assumption was that mothers living away from the toll booths did not experience the beneficial drop in pollution of newly installed E-ZPass.

Although Currie and Reed were unable to collect data directly from pollution monitors in all sites of their study, in one location with a monitor, nitrogen oxide fell by about 11% after the EZ-Pass system began. The monitor did not track carbon monoxide unfortunately.

The effect on birth outcomes of less congestion and presumably lower pollution was remarkable. The estimates suggest that among the roughly 30,000 births in the study within 2 kilometers of a toll plaza, 255 premature births and 275 low birth weigh births were averted after E-ZPass went into effect. There is of course some overlap between the low birth weight births and the premature births. Nevertheless, the results are sizable.

Reducing traffic congestion is a cost-effective way to improve not only quality of life, but long-term health benefits as well. Estimates are that traffic congestion cost about $87.2 billion in terms of wasted time and fuel in 2007. But these costs pale in comparison to the costs of low weight births and premature births over a lifetime. A recent Institute of Medicine report finds that premature births costs society about $51,600 per infant (in 2005 dollars) in long-term health and other costs. Hence, reducing the risk of premature births by approximately 7% as Curried and Reed found among the roughly 30,000 births can be valued at about $9.8 to $13 million.

As Currie and Reed note, although it is difficult to know how many of the roughly 4 million babies born each year in the United States are affected by traffic congestions, estimates by the American Housing Survey suggest that 26% of occupied housing units suffer from street noise or other drawbacks due to traffic. Therefore, nationwide, roughly 1 million infants per year could potentially be affected. Reducing prenatal exposure to the pollutants from congestion could reduce preterm births by as many as 8,600 annually, for a cost savings of $444 million per year.

Currie and Reed’s results point to yet another facet of housing and transportation policy in improving the lives of families. Unfortunately, housing that is affordable to low-income families is more often in the path of pollutants. Currie and Reed’s results point to costly and long-lasting ramifications of poor urban planning, including transportation, development, housing, and public transit policies, that leave families breathing bad air.
So as you whiz through the E-ZPass this holiday season, look around and take note of who is living nearby.  They’re the lucky (or luckier) ones. Those who live next to our clogged city freeways are bearing the brunt of our choice to drive.


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