Many central heating, ventilation, and air conditioning (HVAC) systems have energy management and control systems that can regulate airflow and pressures within a building on an emergency response basis. Some modern fire alarm systems may also provide useful capabilities during chemical, biological, and radiological (CBR) events. In some cases, the best response option (given sufficient warning) might be to shut off the building’s HVAC and exhaust systems, thus, avoiding the introduction of a CBR agent from the outside. In other cases, interior pressure and airflow control

may prevent the spread of a CBR agent released in the building and ensure the safety of egress pathways.