Studies show that Prenatal Air Pollution Lowers Children's IQ

So I just read the first article to really make me paranoid ... a new study showed a link between exposure to smog before birth and low IQ in children. I live in Atlanta and, until about two months before I got pregnant, would walk a mile down a really smoggy street to the train station and back 4 times a week for work. Sometimes in July/August even the short walk from the train station to my office building would make me feel sick from the car exhaust. I'm just glad we happened to move to a less busy area right before we got pregnant... but it still makes me a bit paranoid about living in a big city.