Protective Action Criteria
In the United States, the Emergency Management Issues Special Interest Group (EMI SIG) state that "Protective Action Criteria (PACs) are essential components for planning and response to uncontrolled releases of hazardous chemicals. These criteria, combined with estimates of exposure, provide the information necessary to evaluate chemical release events for the purpose of taking appropriate protective actions.
Source: Wikipedia — Protective Action Criteria (CC BY-SA 4.0)