(1) Generic term for actions taken in response to actual or potential health-threatening environmental events such as spills, sudden releases, and asbestos abatement/management problems. (2) An action authorized by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) involving either a short-term removal action or a long-term removal response. This may include but is not limited to removing hazardous materials from a site to an Environmental Protection Agency (EPA)-approved hazardous waste facility for treatment; containing or treating the waste on-site; identifying and removing the sources of groundwater contamination; and halting further migration of contaminants. (3) Any of the following actions taken in school buildings in response to the Asbestos Hazard Emergency Response Act (AHERA) to reduce the risk of exposure to asbestos removal, encapsulation, enclosure, repair, and operations and maintenance.