Urban exploration (often shortened as urbex or UE) is the exploration of man-made structures, usually abandoned ruins or not usually seen components of the man-made environment. Photography and historical interest/documentation are heavily featured in the hobby and, although it may sometimes involve trespassing onto private property, this is not always the case and is of innocent intention. Urban exploration is also commonly referred to as infiltration, although some people consider infiltration to be more closely associated with the exploration of active or inhabited sites. It may also be referred to as draining (when exploring drains), urban spelunking, urban rock climbing, urban caving, or building hacking.
Ventures into abandoned structures are perhaps the most common example of urban exploration. At times, sites are entered first by locals and may suffer from large amounts of graffiti and other acts of vandalism. Although targets of exploration vary from one country to another, high-profile abandonment include amusement parks, grain elevators, factories, power plants, missile silos, fallout shelters, hospitals, asylums, schools, poor houses, and sanatoriums.
Urban exploration is a hobby that comes with a number of inherent dangers. For example, storm drains are not designed with human access as their primary use. They can be subject to flash flooding and bad air. There have been a number of deaths in storm water drains, but these are usually during floods, and the victims are normally not urban explorers.
Many old abandoned structures feature hazards such as unstable structures, unsafe floors, broken glass, the presence of unknown chemicals and other harmful substances (most notably asbestos), stray voltage, and entrapment hazards. Other risks include freely-roaming guard dogs and hostile squatters. Some abandoned locations may be heavily guarded with motion detectors and active security patrols. Others are more easily accessible and carry less risk of discovery.
Asbestos is a long term health risk for urban explorers, along with breathing in contaminants from dried bird feces, which can cause a condition known as pigeon-breeder’s lung, a form of hypersensitivity pneumonitis. Urban explorers may use dust masks and respirators to alleviate this danger. Some sites are occasionally used by substance abusers for either recreation or waste disposal, and there may be used or infected syringe needles en route, such as those commonly used with heroin.