Feb. 5, 2010 — Traffic congestion may increase the risk of extra weight
gain and obesity among children living in heavy traffic areas, new research
indicates.

“When it’s not safe to play outside, kids are more likely to stay inside and
play computer games or watch television,” lead author Michael Jerrett, PhD, of
the University of California-Berkeley, says in a news release. “These sedentary
habits can put them at greater risk for obesity.”
Jerrett and his team of researchers studied nearly 3,000 children aged 9-10
living in and around Los Angeles for about eight years, until they reached age
18. Researchers collected data annually on the children’s height and weight to
calculate body mass index (BMI). As expected, BMI increased in the children as
they got older, but with children living within 150 meters of traffic, there
was a significant increase in BMIs for girls and boys. “This translates into
about a 5% increase in attained BMI at age 18,” the authors write. “Although
this effect may appear small, the ubiquity of exposure to traffic implies small
changes in the BMI in response to traffic may be associated with impacts on
overweight and obese status in the population.”
The team speculates that children living in traffic-clogged areas may not
walk, bike, or play outside regularly because nearby traffic makes them feel
that being outside is risky. They also suggest a second reason for the
association between traffic density and increased BMI may be related to air
pollution. Because air pollution can negatively impact asthma and lung
function, this may play a role in limiting a child’s ability to be physically
active.
Jerrett and his colleagues, however, suggest that innovative approaches by
city planners could reduce the risk of traffic-related weight gain.
They say measures can and should be taken to increase the “walkability” of
neighborhoods, which perhaps would provide some protection against obesity.
The authors conclude that their study “yields the first evidence of
significant effects from traffic density on BMI (body mass index) levels at age
18 in a large cohort of children. Traffic is a pervasive exposure in most
cities, and our results identify traffic as a major risk factor for the
development of obesity in children.”