When murder rates go down, politicians are quick to claim credit for being tough on crime. When they go up, many on the left blame unemployment. But Economist Rick Nevin has published research suggesting one of the most important factors affecting crime rates may be… pollution. Nevins is a senior advisor to the National Center for Healthy Housing, and author of an ambitious study looking at crime trends and childhood lead exposure around the world. He speaks with Brian Edwards-Tiekert.