After 9/11, Irwin Redlener emerged as a powerful voice in disaster medicine -- the discipline of medical care following natural and human-made catastrophes. He was a leading face of the relief effort after hurricanes Katrina and Rita, and is the author of Americans at Risk: Why We Are Not Prepared for Megadisasters and What We Can Do Now. He's the associate dean, professor of Clinical Public Health and director of the National Center for Disaster Preparedness at Columbia's Mailman School of Public Health.

His parallel passion is addressing the American disaster that happens every day: millions of kids living without proper health care. He and Paul Simon are the co-founders of the Children's Health Fund, which raises money and awareness toward health care for homeless, neglected and poor children.