
An accident is an unintended, normally unwanted event that was not deliberately caused by humans. The term ''accident'' implies that the event may have been caused by
unrecognized or unaddressed risks. Many researchers, insurers and attorneys who specialize in unintentional
injury
Injury is physiological damage to the living tissue of any organism, whether in humans, in other animals, or in plants.
Injuries can be caused in many ways, including mechanically with penetration by sharp objects such as teeth or with ...
prefer to avoid using the term ''accident'', and focus on conditions that increase risk of severe injury or that reduce injury incidence and severity. For example, when a tree falls down during a
wind storm
A storm is any disturbed state of the natural environment or the atmosphere of an astronomical body. It may be marked by significant disruptions to normal conditions such as strong wind, tornadoes, hail, thunder and lightning (a thunderstorm) ...
, its fall may not have been directly caused by
human error
Human error is an action that has been done but that was "not intended by the actor; not desired by a set of rules or an external observer; or that led the task or system outside its acceptable limits".Senders, J.W. and Moray, N.P. (1991) Human Er ...
, but the tree's type, size, health, location, or improper maintenance may have contributed to the result. Most
car crashes
A traffic collision, also known as a motor vehicle collision, or car crash, occurs when a vehicle collision, collides with another vehicle, pedestrian, animal, road debris, or other moving or stationary obstruction, such as a tree, Utility pole ...
are the result of dangerous behavior and not purely ''accidents''; however, English speakers started using that word in the mid-20th century as a result of
media manipulation
Media manipulation refers to orchestrated campaigns in which actors exploit the distinctive features of broadcasting mass communications or digital media platforms to mislead, misinform, or create a narrative that advances their interests and ag ...
by the US automobile industry.
Accidental deaths were much less frequent before high-powered machinery began to spread with the
Industrial Revolution
The Industrial Revolution, sometimes divided into the First Industrial Revolution and Second Industrial Revolution, was a transitional period of the global economy toward more widespread, efficient and stable manufacturing processes, succee ...
of the late 1700s.
In recent years worldwide, the most-common causes of
accidental death
An accidental death is an unnatural death that is caused by an accident, such as a slip and fall, traffic collision, or accidental poisoning. Accidental deaths are distinguished from death by natural causes, disease, and from intentional homici ...
s are road traffic and
falls. Many different theoretical models have been proposed for analyzing accidents, but no single model has yet proved sufficient for these often-complex events.
Types
Physical and non-physical
Physical examples of accidents include unintended motor vehicle collisions, malfunctioning machinery, drowning, falling, or unintentional contact with something sharp or hot or electrified or poisonous (including drug overdoses).
Non-physical examples include unintentionally revealing a
secret
Secrecy is the practice of hiding information from certain individuals or groups who do not have the "need to know", perhaps while sharing it with other individuals. That which is kept hidden is known as the secret.
Secrecy is often controver ...
or otherwise saying something incorrectly, or forgetting an appointment.
Work and leisure
Accidents during the course of work, or arising out of it, are called
work accident
A work accident, workplace accident, occupational accident, or accident at work is a "discrete occurrence in the course of work" leading to physical or mental occupational injury. According to the International Labour Organization (ILO), more th ...
s, occupational accidents, or similar terms. According to the
International Labour Organization
The International Labour Organization (ILO) is a United Nations agency whose mandate is to advance social and economic justice by setting international labour standards. Founded in October 1919 under the League of Nations, it is one of the firs ...
, approximately 400 million accidents happen on the job each year (5% of the world population), causing more than 300,000 deaths annually (especially in mining and construction) and millions of long-term
disabilities
Disability is the experience of any condition that makes it more difficult for a person to do certain activities or have equitable access within a given society. Disabilities may be cognitive, developmental, intellectual, mental, physica ...
(especially
back injuries
Back injuries result from damage, wear, or trauma to the bones, muscles, or other tissues of the back. Common back injuries include sprains and strains, herniated discs, and fractured vertebrae. The lumbar spine is often the site of back pain. ...
).
In contrast,
leisure
Leisure (, ) has often been defined as a quality of experience or as free time. Free time is time spent away from business, Employment, work, job hunting, Housekeeping, domestic chores, and education, as well as necessary activities such as ...
-related accidents are mainly
sports injuries
Sports injuries occur during participation in sports or exercise in general. Globally, around 40% of individuals engage in some form of regular exercise or organized sports, with upwards of 60% of US high school students participating in one or ...
, with lower fatality rates.
In
process manufacturing
Process manufacturing is a branch of manufacturing that is associated with formulas and manufacturing recipes, , a primary accident (such as leakage, fire or explosion) may propagate to nearby units, resulting in an escalating chain of failure, which is often called a
domino effect accident
A domino effect accident is an accident in which a primary undesired event sequentially or simultaneously triggers one or more secondary undesired events in nearby equipment or facilities, leading to secondary accidents more severe than the primary ...
.
Commercial products sometimes emerge from accidental discoveries, famously including
penicillin
Penicillins (P, PCN or PEN) are a group of beta-lactam antibiotic, β-lactam antibiotics originally obtained from ''Penicillium'' Mold (fungus), moulds, principally ''Penicillium chrysogenum, P. chrysogenum'' and ''Penicillium rubens, P. ru ...
,
Post-it note
A Post-it note (or sticky note) is a small piece of paper with a re-adherable strip of glue on its back, made for temporarily attaching notes to documents and other surfaces. A low-adhesion, tack pressure-sensitive adhesive allows the notes to ...
s, and
microwave oven
A microwave oven, or simply microwave, is an electric oven that heats and cooks food by exposing it to electromagnetic radiation in the microwave frequency range. This induces Dipole#Molecular dipoles, polar molecules in the food to rotate and ...
s. Injuries that occur during travel to or from employment are sometimes counted statistically as work accidents, but are usually classified separately as transportation accidents instead.
Transportation
Aviation
Aviation safety
Aviation safety is the study and practice of managing risks in aviation. This includes preventing aviation accidents and incidents through research, educating air travel personnel, passengers and the general public, as well as the design of airc ...
has improved dramatically through decades of concerted effort. Although individual crashes can have high fatality counts and widespread publicity, modern air travel has approximately just 1 fatal crash per 16 million commercial flights (as of 2024), or 1 death per 35 billion passenger-kilometers (22 billion miles), far better than historical rates, and generally the safest way to travel a given distance over land. Airplane accidents occur most commonly during the landing process.
Bicycles and motorcycles
Unenclosed two-wheel vehicles are more economical but less visible than the much larger cars and trucks on the road, and bikes offer their riders little protection from collision or weather or hazardous road conditions. For these reasons, bicycle or motorcycle travel typically has multiple times the risk of car travel over a given distance.
Electric bike
An electric bicycle, e-bike, electrically assisted pedal cycle, or electrically power assisted cycle is a bicycle with an integrated electric motor used to assist propulsion. Many kinds of e-bikes are available worldwide, but they generally fa ...
s present the further risk of accidental fire from the overheating of their powerful batteries, especially from lower-quality manufacturers.
Maritime
Water transportation accidents are far too diverse for any simple generalization or statistic. Modern
mega-cruise ships are akin to slow-motion cities, where accidental deaths are dwarfed by ordinary heart attacks and strokes. At the opposite extreme of size, technology, and regulation,
refugee boats and
whitewater kayaks are much riskier than luxury cruise ships.
Ferries
A ferry is a boat or ship that transports passengers, and occasionally vehicles and cargo, across a body of water. A small passenger ferry with multiple stops, like those in Venice, Italy, is sometimes referred to as a water taxi or water bus.
...
overloaded with impoverished crowds capsize regularly, and so do the
sailboat
A sailboat or sailing boat is a boat propelled partly or entirely by sails and is smaller than a sailing ship. Distinctions in what constitutes a sailing boat and ship vary by region and maritime culture.
Types
Although sailboat terminology ...
s of wealthy adventurers, and
cargo ship
A cargo ship or freighter is a merchant ship that carries cargo, goods, and materials from one port to another. Thousands of cargo carriers ply the world's List of seas, seas and Ocean, oceans each year, handling the bulk of international trade. ...
s in hazardous waters. Any attempt to summarize maritime accidents would need to recognize all these differences and more.

Road traffic
Most vehicle collisions are triggered by preventable driver behaviors such as
drunk
Alcohol intoxication, commonly described in higher doses as drunkenness or inebriation, and known in overdose as alcohol poisoning, is the behavior and physical effects caused by recent consumption of alcohol. The technical term ''intoxication ...
,
drowsy
Somnolence (alternatively sleepiness or drowsiness) is a state of strong desire for sleep, or sleeping for unusually long periods (compare hypersomnia). It has distinct meanings and causes. It can refer to the usual state preceding Sleep onset, fa ...
,
distracted, or
dangerously fast driving, and are not true accidents in the strictest sense. The use of the word ''accident'' to describe car wrecks was promoted by the US
National Automobile Chamber of Commerce
National may refer to:
Common uses
* Nation or country
** Nationality – a ''national'' is a person who is subject to a nation, regardless of whether the person has full rights as a citizen
Places in the United States
* National, Maryland, ce ...
in the middle of the 20th century, as a way to make vehicle-related deaths and injuries seem like an unavoidable matter of fate, rather than a problem that could be addressed by
automotive safety
Automotive safety is the study and practice of automotive design, construction, equipment and regulation to minimize the occurrence and consequences of traffic collisions involving motor vehicles. Road traffic safety more broadly includes roadw ...
. The automobile industry accomplished this by writing customized articles about local collisions as a free service for newspapers that used the industry's preferred language. Since 1994, the US
National Highway Traffic Safety Administration
The National Highway Traffic Safety Administration (NHTSA ) is an agency of the U.S. federal government, part of the Department of Transportation, focused on automobile safety regulations.
NHTSA is charged with writing and enforcing Feder ...
has asked media and the public not to use the word ''accident'' to describe vehicle collisions.

Trains
For a given distance,
passenger train
A passenger train is a train used to transport people along a railroad line, as opposed to a freight train that carries goods. These trains may consist of unpowered passenger railroad cars (also known as coaches or carriages) push-pull train, ...
s (and also buses) are considerably safer than car traffic, although riskier than commercial aircraft. Major rail accidents can also arise from
freight train
A freight train, also called a goods train or cargo train, is a railway train that is used to carry cargo, as opposed to passengers. Freight trains are made up of one or more locomotives which provide propulsion, along with one or more railroad ...
s, carrying bulk quantities of
hazardous cargo but few people. Unlike most other transportation accidents, a large fraction of train casualties are people out along the route, not riding on the train itself.
Common causes

According to the
World Health Organization
The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Gen ...
, globally more than 3 million
accidental death
An accidental death is an unnatural death that is caused by an accident, such as a slip and fall, traffic collision, or accidental poisoning. Accidental deaths are distinguished from death by natural causes, disease, and from intentional homici ...
s occur in a typical year. The most-common causes are road traffic (1.2 million annual deaths, especially for young males) and falls (0.7 million annual deaths, especially for elderly females). Both fatal and nonfatal accident rates in developing countries are at least double the per-capita rates in high-income countries.
The United States collects detailed statistical injury data (sampled from 100 hospitals) through the National Electronic Injury Surveillance System administered by the
Consumer Product Safety Commission
The United States Consumer Product Safety Commission (USCPSC, CPSC, or commission) is an independent agency of the United States government. The CPSC seeks to promote the safety of consumer products by addressing "unreasonable risks" of injury ...
. This program was revised in 2000 to include all injuries, rather than just injuries involving products. Data on
emergency department
An emergency department (ED), also known as an accident and emergency department (A&E), emergency room (ER), emergency ward (EW) or casualty department, is a medical treatment facility specializing in emergency medicine, the Acute (medicine), ...
visits is also collected through the annual
National Health Interview Survey
The National Health Interview Survey (NHIS) is an annual, cross-sectional survey intended to provide nationally representative estimates on a wide range of health status and utilization measures among the nonmilitary, noninstitutionalized popula ...
by the
CDC
The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency under the Department of Health and Human Services (HHS), and is headquartered in Atlanta, ...
's
National Center for Health Statistics
The National Center for Health Statistics (NCHS) is a U.S. government agency that provides statistical information to guide actions and policies to improve the public health of the American people. It is a unit of the Centers for Disease Control ...
. The US
Bureau of Labor Statistics
The Bureau of Labor Statistics (BLS) is a unit of the United States Department of Labor. It is the principal fact-finding agency for the government of the United States, U.S. government in the broad field of labor economics, labor economics and ...
website includes extensive data on workplace accidents.
Analytical models
Many theoretical models to characterize and analyze accidents have been proposed, which can be classified by type. Most accidents have no single cause, and no single model is the sole correct approach for analyzing them. Notable models include:

* Sequential models
** Domino theory
** Loss causation model
* Complex linear models
** Energy damage model
** Time sequence models
*** Generalized time sequence model
[
*** Accident evolution and barrier function
** Epidemiological models
*** Public health analysis
*** "Resident pathogens" metaphor
* Process models
** Multilinear events sequencing
* Systemic models
** Skill/Rule/Knowledge model of human error
** Reason's model of system safety (embedding the ]Swiss cheese model
The Swiss cheese model of accident causation is a model used in Risk analysis (engineering), risk analysis and risk management. It likens human systems to multiple slices of Swiss cheese (North America), Swiss cheese, which have randomly placed an ...
)
*** Healthcare error proliferation model
*** Human reliability
In the field of human factors and ergonomics, human reliability (also known as human performance or HU) is the probability that a human performs a task to a sufficient standard. Reliability of humans can be affected by many factors such as age, ...
** Human/Machine cognitive systems
* Non-linear models
** System accident
A system accident (or normal accident) is an "unanticipated interaction of multiple failures" in a complex system. This complexity can either be of technology or of human organizations and is frequently both. A system accident can be easy to see ...
** Systems-theoretic accident model and process (STAMP)
** Functional resonance analysis method (FRAM)
** Assertions that all existing models are insufficient for complex systems
Ishikawa diagram
Ishikawa diagrams (also called fishbone diagrams, herringbone diagrams, cause-and-effect diagrams) are causal diagrams created by Kaoru Ishikawa that show the potential causes of a specific event.
Common uses of the Ishikawa diagram are produc ...
s are sometimes used to illustrate root-cause analysis and five whys
Five whys (or 5 whys) is an iterative interrogative technique used to explore the cause-and-effect relationships underlying a particular problem. The primary goal of the technique is to determine the root cause of a defect or problem by repeati ...
discussions.
See also
* Accident insurance
Accident insurance is a type of insurance where the policy holder is paid directly in the event of an accident resulting in injury of the insured. The insured can spend the benefit payment however they choose. Accident insurance is complementary to ...
* Accident-proneness
Accident-proneness is the idea that some people have a greater predisposition than others to experience accidents, such as car crashes and industrial injuries. It may be used as a reason to deny any insurance on such individuals.
Early work
The e ...
* Act of God
In legal usage in the English-speaking world, an act of God, act of nature, or damnum fatale ("loss arising from inevitable accident") is an event caused by no direct human action (e.g. Severe weather, severe or extreme weather and other natur ...
* Fail-safe
In engineering, a fail-safe is a design feature or practice that, in the event of a failure causes, failure of the design feature, inherently responds in a way that will cause minimal or no harm to other equipment, to the environment or to people. ...
* Idiot-proof
An idiot-proof or foolproof design is one that cannot be misused either inherently, or by use of defensive design principles. The implication is that the design is usable even by someone of low intelligence who would not use it properly.
The t ...
* Injury prevention
Injury prevention is an effort to prevent or reduce the severity of bodily injury, bodily injuries caused by external mechanisms, such as accidents, before they occur. Injury prevention is a component of safety and public health, and its goal is ...
* Lists of disasters
The following are lists of disasters.
Natural disasters
A natural disaster is the highly harmful impact on a society or community following a natural hazard event. These lists are lists of natural disasters:
* List of avalanches
* Lis ...
* Personal protective equipment
Personal protective equipment (PPE) is protective clothing, helmets, goggles, or other garments or equipment designed to protect the wearer's body from injury or infection. The hazards addressed by protective equipment include physical, elect ...
* Poka-yoke
is any mechanism in a process that helps an equipment operator to avoid mistakes and defects by preventing, correcting, or drawing attention to human errors as they occur. It is a Japanese term that means "mistake-proofing" or "error prevention", ...
* Risk management
Risk management is the identification, evaluation, and prioritization of risks, followed by the minimization, monitoring, and control of the impact or probability of those risks occurring. Risks can come from various sources (i.e, Threat (sec ...
* Safety
Safety is the state of being protected from harm or other danger. Safety can also refer to the control of recognized hazards in order to achieve an acceptable level of risk.
Meanings
The word 'safety' entered the English language in the 1 ...
* Safety engineering
Safety engineering is an engineering Branches of science, discipline which assures that engineered systems provide acceptable levels of safety. It is strongly related to industrial engineering/systems engineering, and the subset system safety en ...
References
External links
{{Authority control
Safety