Just what is ozone, and why is everyone worried about it? Richard Zurek of NASA's Jet Propulsion Laboratory explains how chlorofluorocarbons (CFCs) destroy ozone and why this is an international problem. Ozone filters out ultraviolet rays, and if the ozone layer disappears everyone will get a heck of a sunburn. Research continues on how ozone protects the earth and how human activity contributes to atmospheric changes.