The fire service uses rescue vehicles to transport specialized firefighters to and from structural fires as well as a variety of specialty events such as high angle rescue, confined space rescue, trench rescue, and hazardous materials responses. The National Urban Search and Rescue program has specific designs for such equipment. Command vans and communication vehicles are also extremely common in all major metropolitan fire departments. The United States fire service is the nation's foremost emergency medical provider and uses various on-road and off-road ambulance vehicles. Other specialty vehicles in the fire service are air units which supply breathing air to firefighters; brush trucks for wildland firefighting; lighting vehicles; mobile ventilation vehicles; rehabilitation vehicles; fuel vehicles; and mobile mechanical support units.