An emergency exit in a structure is a special exit for emergencies such as a fire: the combined use of regular and special exits allows for faster evacuation, while it also provides an alternative if the route to the regular exit is blocked by fire, etc.
It is usually a strategically located (e.g. in a stairwell, hallway, or other likely place) outward opening door with a crash bar on it and with exit signs leading to it. The name is a reference to when they are frequently used, however a fire exit can also be a main doorway in or out. A fire escape is a special kind of emergency exit, mounted to the outside of a building.
 Building code regulations
Local building codes will often dictate the number of fire exits required for a building of a given size. This may include specifying the number of stairs. For any building bigger than a private house, modern codes invariably specify at least two sets of stairs. Furthermore, such stairs must be completely separate from each other. Some architects meet this requirement by housing two stairs in a "double helix" configuration where two stairs occupy the same floor space, intertwined. It may make no functional sense to have two stairs so close to each other, but it meets the requirements of the building codes.
Knowing where the emergency exits are in buildings can save your life. Some buildings, such as schools, have fire drills to practice using emergency exits. Many disasters could have been prevented if people had known where fire escapes were, and if emergency exits had not been blocked. For example, in the September 11, 2001 attacks on the World Trade Center, some of the emergency exits inside the building were inaccessible, while others were locked. In the Stardust Disaster and the 2006 Moscow hospital fire the emergency exits were locked and most windows barred shut. In the case of the Station Nightclub, the premises was over capacity the night fire broke out, the front exit was not designed well (right outside the door, the concrete approach split 90 degrees and a railing ran along the edge, and an emergency exit swung inward, not outward as code requires).
In many countries, it is required that all new commercial buildings include well-marked emergency exits. Older buildings must be retrofitted with fire escapes. In countries where emergency exits are not standard, fires will often result in a much greater loss of life.
Well-designed emergency exit signs are necessary for emergency exits to be effective.
In many countries fire escape signs usually display the word "EXIT" in large, well-lit, green or red letters, but the pictorial "running green man" symbol developed in 1980 and introduced in 2003 by ISO 7010 is universal in the European Union, the standard in Canada from 2010, and increasingly common elsewhere.
 Problems with emergency exits
Fire fighters have cited overzealous guards who told people during a fire that they are not allowed to use emergency exits. The practice is actually quite common in the absence of fires, as well. Some skyscrapers have stairwells with standard emergency exit signs on each door, which then lock upon closing. Users of these stairwells are trapped, whether they know or do not know that the only door that opens from the inside is the one on the ground floor.
A further problem becoming very common in the USA (2005) is that retail stores at night close one of their main entrance/exits through makeshift heavy metal barriers, signage, paper notes, or junk placed in front of the exits. Some actually lock their exits. A large array of signage and mechanical exit systems have also been devised, including signage that says contradictorily, "This is not an exit," "Do not use this exit," or warning users that a heavy penalty will be assessed for non-emergency use.
Some systems do not allow the exit to be opened until the user signals the intention to exit (through a button or lever) for some amount of time, such as 20 seconds. It is also common for these exits to remain completely locked until somebody tests them.
The need for civic building code regulations became headline news in the early 20th century after a series of disasters that resulted from inadequate emergency exits. The Triangle Shirtwaist Factory fire in 1911 remains the worst industrial accident in New York City history; 146 factory workers died during a fire when they were stopped by locked emergency exits, or when they fell to their deaths from a flimsy fire escape that collapsed.
492 people died in the deadliest nightclub fire in U.S. history, the Cocoanut Grove fire in Boston in 1942. Guests could only exit through a revolving door, which became blocked during the stampede to escape the fire. There are now regulations requiring that exits of large buildings open outward, and that enough emergency exits are provided to accommodate the building's capacity.
Similar disasters around the world have resulted in public fury and calls for changes to emergency regulations and enforcement. An investigation was launched by the Argentine federal government after 194 people were killed during the 2004 República Cromañón nightclub fire in Buenos Aires, Argentina. The emergency exits had been chained shut by the owners, to prevent people from sneaking into the nightclub without paying.
 On aircraft
In aircraft terms, an "exit" is any one of the main doors (entry doors on the port side of the aircraft and service doors on the starboard side) and an "emergency exit" is defined as a door that is only ever used in an emergency (such as overwing exits and permanently armed exits). Passengers seated in exit rows may be called upon to assist and open exits in the event of an emergency.
The number and type of exits on an aircraft is regulated through strict rules within the industry, and is based on whether the aircraft is single or twin-aisled; the maximum passenger load; and the maximum distance from a seat to an exit. The goal of these regulations is to make possible the evacuation of an airliner's designed maximum occupancy of passengers and crew within 90 seconds even if half of the available exits are blocked.
Any aircraft where the emergency exit door sill height is above that which would make unaided escape possible is fitted with an automatic inflatable evacuation slide, which allows occupants to slide to the ground safely.
 Various types of emergency exits
Some have alarms activated when they open to alert staff of unauthorized use.
Red Exit Sign in the United States
An exit sign on a school bus
Emergency light with an emergency exit pictogram
Overwing emergency exit of a Boeing 737.
Emergency Exit sign printed in red colour on the walls of flats in Saudi Arabia
- Or the equivalent word in the local language
- ISO 7010:2011 — Graphical symbols
- "The Big Red Word vs. the Little Green Man", Julia Turner, March 2010, Slate.com
- Traditional Signs to EXIT in Favour of the Running Man
- Reel, Monte (January 1, 2005). "Fire, panic, and a locked main exit". Washington Post. Retrieved July 11, 2012.
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- US2,724,258 – Fire exit lock