What is the procedure involving closing all windows and ensuring HVAC systems remain operational?

The procedure involving closing all windows and ensuring HVAC systems remain operational is known as shelter-in-place protection. This approach is typically used in situations where there is a release of hazardous materials into the environment, such as during a chemical leak or an airborne contaminant incident.

When sheltering in place, the main goal is to minimize exposure to potentially harmful substances while remaining indoors. Closing windows and doors helps to create a barrier against outside contaminants, and keeping HVAC systems operational (or, in some cases, shutting them down if they can introduce contaminants) is crucial for maintaining air quality and controlling the indoor environment. This procedure allows individuals to stay safely inside until it is deemed safe to leave or until the situation has been resolved.

In contrast, other options like evacuation involve leaving the area entirely, lockdown procedures typically pertain to security threats, and site isolation refers to restricting access to an area where a hazardous material incident has occurred. Each of these options serves different purposes and is utilized in distinct emergency scenarios.