on shift, the firefighter remains at the fire station unless relieved or assigned other duties. Fire wardens In fire fighting, there are also people designated as fire wardens, also known as chief officers. Their duties vary, some may ensure evacuation of that part of the building for which they are responsible; others may be responsible for fire control in a particular area, direct a crew in the suppression of forest fires, or function as fire patrolmen in a logging area. The chief officer is in charge of their firefighters during fires or emergencies, and is expected to command and control the overall situation while effectively combating a fire or other emergency. Chief officers must be able to evaluate their firefighters, use sound judgement when deciding when it is time to withdraw firefighters from a fire, and react calmly in emergency situations. The chief officer must direct the activities of a fire department and supervise all firefighting activities, requiring extensive knowledge of city layouts, the location of streets, fire hydrants and fire alarm boxes, and the principal buildings. A chief officer must be familiar with sources of fires, including explosives, hazardous chemicals, and the combustion qualities of materials in buildings, homes, and industrial plants. In certain jurisdictions, civilians can get certified to be a Fire Warden, and some cities require certain types of buildings, such as high rises, to have a certain number of Fire Wardens. For example, the city of Houston in the United States requires every tenant in a high-rise to have at least one Fire Warden for every 7500 sq. ft. occupied, and a minimum of two Fire Wardens per floor. In this example, their duties include investigating any fire alarms (see if there really is a fire and if so, its nature), ensuring the fire department is contacted, directing the evacuation of the facility, activating or delaying activation of fire suppression equipment such as halon and sprinklers (delayed in case of a false alarm), meeting the fire department and taking them to the location of the alarm or to the fire past any security or locked doors, and, if necessary, fighting the fire until the fire department arrives. Hazards caused by fire During a fire One of the major hazards associated with firefighting operations is the toxic environment created by combusting materials. The four major hazards are: Smoke, which is becoming increasingly dangerous due to the increased