More than 11 million Americans live within 150 meters of highways, which generate high levels of air and noise pollution.
is a particularly important one as it can lead to immediate consequences, like trouble breathing, and long-term issues across the life course, like cardiovascular disease, cognitive impacts, and premature mortality,” said Willis. For the first time, the team was able to draw a link between traffic congestion and pregnancy outcomes in nearby neighborhoods in the U.S.
Willis and her colleagues examined the relationship between traffic congestion and the outcomes of 579,122 births in addresses within 500 meters of road segments in Texas, from 2015 to 2016. In this data, they found a strong correlation between traffic congestion and lower birth weights, with birth weights on average 9 grams lower in the highest quintile of exposure to traffic delay.
“A 9-gram decrease alone isn’t a clinically significant result, but this result indicates that some sort of biological impacts may be happening, which will push some babies into a clinically relevant adverse impact,” Willis said. “When you multiply that by 27 percent of all births being in high congestion areas, that small decrease in birthweight does translate into a substantial potential impact at the population level, affecting up to 1.3 million babies per year.
According to Willis, one of the surprising results of this study is a whole new way to measure exposure that was separate from tailpipe emissions from a vehicle. Instead, this metric focused on the process of delay on the road. “Traffic engineers and urban planners can parse this data to figure out where vehicle speed is slower than expected, which indicates traffic congestion and delay.