An event qualifies as a "community health emergency" when it involves a disease outbreak, environmental release of a toxin, or a bioterrorism attack that actually or potentially places a large segment of the community at risk for physical impairment and even death. Such an event causes sufficient patient surge or presents patients for medical care in such a way that it significantly strains and disrupts the healthcare system. Healthcare delivery may also be undermined because health care facilities are damaged or made inaccessible. In discussing ways to prevent or reduce such healthcare emergencies, this paper focuses on hazard-resistant healthcare facilities; surveillance for detecting symptoms of potentially large-scale disease and toxic effects; diagnosis and investigation; the stockpiling of vaccines, drugs, and diagnostic tools; and disease containment. Other issues addressed are patient movement, mass decontamination and prophylaxis, mass care, and information and communication. The paper notes that there is a need for research on many of these components of health-emergency planning, as well as on modes of integrating them. 10 references