With GEOSS, we can envision a world in which the health community and public will easily access timely, comprehensive information to make real-time health decisions. Knowing that El Niño brings cholera outbreaks each warm weather cycle already gives the health community a much better shot at getting ahead of the curve. AirNOW is making daily real-time air quality data meaningful to policymakers and the public and becoming an international model. As GEOSS creates opportunities to discover early indicators of harmful conditions and predictive models improve, other preventative measures will emerge. Earth observations of weather, land, and ocean parameters will help predict outbreaks and trends in meningitis, malaria, and other diseases. Data on weather and stream flow will be factored into better management of drinking water. Improved data on food contaminants, ultraviolet radiation, and chemical emissions will contribute to prevention, early warning, and more rapid problem-solving.