Jerrett: Our study looks at the impact of traffic density in proximity to children's homes and we control for a wide range of individual and build environment factors that are thought to influence the progression of BMI.
Narrator: Children who live in neighborhoods that have a lot of traffic around their homes tend to have higher BMIs by the time they are 18 than those who live in lower traffic areas.
Jerrett: Traffic in and of itself exerts an effect that's significant and the effect size is about five to 10 percent. That might not sound like a lot, but given that this is a global problem and that traffic is such a pervasive exposure, we could have a very big burden of illness.
Narrator: For Science Today, I'm Larissa Branin.