Randi Hutter Epstein received her M.D. from Yale University; she teaches journalism at Columbia University's graduate school. Nina Berman hide caption

itoggle caption Nina Berman

Bob Karch is the chairman and a professor in the Department of Health and Fitness at American University. Here, he helps cross-country champion Steve Hallinan check his heart rate while cross-training on the bike. Allison Aubrey/NPR hide caption

itoggle caption Allison Aubrey/NPR

Studies show that only about 40 percent of health care workers in the U.S. wash their hands as often as they should. Rob Carr/AP hide caption

itoggle caption Rob Carr/AP

According to a study of four jurisdictions that have banned the use of hand-held devices while driving, the laws have not reduced accident rates. iStockphoto.com hide caption

itoggle caption iStockphoto.com

A woman receives treatment in a U.S.-run emergency clinic in Port-au-Prince. John W. Poole/NPR hide caption

itoggle caption John W. Poole/NPR

A barefooted runner takes to the streets. Charlie Riedel/AP hide caption

itoggle caption Charlie Riedel/AP