What is the recommended action involving heating, ventilation, and air-conditioning systems during a hazardous material incident?

During a hazardous material incident, the recommended action regarding heating, ventilation, and air-conditioning systems is to implement "sheltering in place." This approach involves sealing the building and minimizing airflow to protect occupants from exposure to hazardous materials outside. By maintaining the indoor environment and addressing the HVAC systems effectively, you can reduce the infiltration of contaminated air, thereby providing a safer space for those inside.

Sheltering in place acknowledges that evacuation may not always be feasible or safe, especially if external conditions are dangerous, such as the presence of toxic fumes or other harmful agents in the environment. By controlling ventilation and sealing windows and doors, you create a controlled atmosphere that limits exposure to hazardous materials.

While sealing the building and emergency ventilation are important components of this strategy, the overall action of sheltering in place effectively encompasses these measures, ensuring that it is not only about sealing but also about maintaining the safety and health of individuals within the structure until the situation is resolved.