Safety is the state of being "safe" (from French sauf), the condition of being protected against physical, social, spiritual, financial, political, emotional, occupational, psychological, educational or other types or consequences of failure, damage, error, accidents, harm or any other event which could be considered non-desirable. This can take the form of being protected from the event or from exposure to something that causes health or economical losses. It can include protection of people or of possessions.
There also are two slightly different meanings of safety
, for example, home safety
may indicate a building's ability to protect against external harm events (like weather, home invasion, etc), and the second that its internal installations (like appliances, stairs, etc) are safe (not dangerous or harmful) for its habitants.
Safety can be limited in relation to some guarantee
or a standard of insurance
to the quality and unharmful function of an object or organization. It is used in order to ensure that the object or organization will do only what it is meant to do.
It's important to realize that safety is relative. Eliminating all risk, if even possible, would be extremely difficult and very expensive. A safe situation is one where risks of injury or property damage are low and manageable.
Types of safety
It is important to distinguish between products that meet standards, that are safe, and those that merely feel safe. The highway safety community uses these terms:
is a term used to describe products or designs that meet applicable design standards.
means that the real-world safety history is favorable, whether or not standards are met.
refers to the level of comfort of users. For example, traffic signals are perceived as safe, yet under some circumstances, they can increase traffic crashes at an intersection. Traffic roundabouts have a generally favorable safety record, yet often make drivers nervous.
Risks and responses
Safety is generally interpreted as implying a real and significant impact on risk of death, injury or damage to property. In response to perceived risks many interventions may be proposed with engineering responses and regulation being two of the most common.
Probably the most common individual response to perceived safety issues is insurance, which compensates for or provides restitution in the case of damage or loss.
System safety and reliability engineering
engineering is an engineering discipline. Continuous changes in technology, environmental regulation and public safety concerns make the analysis of complex safety-critical
systems more and more demanding.
A common fallacy, for example among electrical engineers regarding structure power systems, is that safety issues can be readily deduced. In fact, safety issues have been discovered one by one, over more than a century in the case mentioned, in the work of many thousands of practitioners, and cannot be deduced by a single individual over a few decades. A knowledge of the literature, the standards and custom in a field is a critical part of safety engineering. A combination of theory and track record of practices is involved, and track record indicates some of the areas of theory that are relevant. (In the USA, persons with a state license in Professional Engineering in Electrical Engineering are expected to be competent in this regard, the foregoing notwithstanding, but most electrical engineers have no need of the license for their work.)
Safety is often seen as one of a group of related disciplines: quality, reliability, availability, maintainability and safety. (Availability is sometimes not mentioned, on the principle that it is a simple function of reliability and maintainability.) These issues tend to determine the value of any work, and deficits in any of these areas are considered to result in a cost, beyond the cost of addressing the area in the first place; good management is then expected to minimize total cost.
are activities and precautions taken to improve safety, i.e. reduce risk related to human health. Common safety measures include:
- Root cause analysis to identify causes of a system failure and correct deficiencies.
- Visual examination for dangerous situations such as emergency exits blocked because they are being used as storage areas.
- Visual examination for flaws such as cracks, peeling, loose connections.
- Chemical analysis
- X-ray analysis to see inside a sealed object such as a weld, a cement wall or an airplane outer skin.
- Destructive testing of samples
- Stress testing subjects a person or product to stresses in excess of those the person or product is designed to handle, to determining the "breaking point".
- Safety margins/Safety factors. For instance, a product rated to never be required to handle more than 200 pounds might be designed to fail under at least 400 pounds, a safety factor of two. Higher numbers are used in more sensitive applications such as medical or transit safety.
- Implementation of standard protocols and procedures so that activities are conducted in a known way.
- Training of employees, vendors, product users
- Instruction manuals explaining how to use a product or perform an activity
- Instructional videos demonstrating proper use of products
- Examination of activities by specialists to minimize physical stress or increase productivity
- Government regulation so suppliers know what standards their product is expected to meet.
- Industry regulation so suppliers know what level of quality is expected. Industry regulation is often imposed to avoid potential government regulation.
- Self-imposed regulation of various types.
- Statements of Ethics by industry organizations or an individual company so its employees know what is expected of them.
- Drug testing of employees, etc.
- Physical examinations to determine whether a person has a physical condition that would create a problem.
- Periodic evaluations of employees, departments, etc.
- Geological surveys to determine whether land or water sources are polluted, how firm the ground is at a potential building site, etc.
A number of standards organizations
exist that promulgate safety standards. These may be voluntary organizations or government agencies.
American National Standards Institute
A major American standards organization
is the American National Standards Institute
(ANSI). Usually, members of a particular industry will voluntarily form a committee to study safety issues and propose standards. Those standards are then recommended to ANSI, which reviews and adopts them. Many government regulations require that products sold or used must comply with a particular ANSI standard.
Product safety testing, for the United States, is largely controlled by the Consumer Product Safety Commission. In addition, work-place related products come under the jurisdction of OSHA, which certifies independent testing companies as Nationally Recognized Testing Laboratories (NRTL), see
For other countries, there are many other organizations that have accreditation to test and/or submit test reports for safety certification. These are typically referred to as a Notified or Competent Body. The most common is the IECEE Certification Body Scheme, see
Many government agencies set safety standards for matters under their jurisdiction, such as: