Permissible Exposure Limit
Encyclopedia
The permissible exposure limit (PEL or OSHA PEL) is a legal
limit in the United States
for exposure of an employee to a chemical substance
or physical agent. For chemicals, the chemical regulation
is usually expressed in parts per million (ppm), or sometimes in milligrams per cubic metre
(mg/m3). Units of measure for physical agents such as noise
are specific to the agent. Permissible exposure limits are established by the Occupational Safety and Health Administration
(OSHA).
A PEL is usually given as a time-weighted average (TWA), although some are short-term exposure limit
s (STEL) or ceiling limits. A TWA is the average exposure over a specified period of time, usually a nominal eight hours. This means that, for limited periods, a worker may be exposed to concentrations higher than the PEL, so long as the average concentration over eight hours remains lower.
A short-term exposure limit is one that addresses the average exposure over a 15-30 minute period of maximum exposure during a single work shift. A ceiling limit is one that may not be exceeded for any period of time, and is applied to irritants and other materials that have immediate effects.
Law
Law is a system of rules and guidelines which are enforced through social institutions to govern behavior, wherever possible. It shapes politics, economics and society in numerous ways and serves as a social mediator of relations between people. Contract law regulates everything from buying a bus...
limit in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
for exposure of an employee to a chemical substance
Chemical substance
In chemistry, a chemical substance is a form of matter that has constant chemical composition and characteristic properties. It cannot be separated into components by physical separation methods, i.e. without breaking chemical bonds. They can be solids, liquids or gases.Chemical substances are...
or physical agent. For chemicals, the chemical regulation
Regulation of chemicals
The regulation of chemicals is the legislative intent of a variety of national laws or international initiatives such as agreements, strategies or conventions. These international initiatives define the policy of further regulations to be implemented locally as well as exposure or emission limits...
is usually expressed in parts per million (ppm), or sometimes in milligrams per cubic metre
Cubic metre
The cubic metre is the SI derived unit of volume. It is the volume of a cube with edges one metre in length. An alternative name, which allowed a different usage with metric prefixes, was the stère...
(mg/m3). Units of measure for physical agents such as noise
Noise
In common use, the word noise means any unwanted sound. In both analog and digital electronics, noise is random unwanted perturbation to a wanted signal; it is called noise as a generalisation of the acoustic noise heard when listening to a weak radio transmission with significant electrical noise...
are specific to the agent. Permissible exposure limits are established by the Occupational Safety and Health Administration
Occupational Safety and Health Administration
The United States Occupational Safety and Health Administration is an agency of the United States Department of Labor. It was created by Congress of the United States under the Occupational Safety and Health Act, signed by President Richard M. Nixon, on December 29, 1970...
(OSHA).
A PEL is usually given as a time-weighted average (TWA), although some are short-term exposure limit
Short-term exposure limit
The short-term exposure limit is a term used in occupational health, industrial hygiene and toxicology. The STEL may be a legal limit in the United States for exposure of an employee to a chemical substance. The Occupational Safety and Health Administration has set OSHA-STELs for 1,3-Butadiene,...
s (STEL) or ceiling limits. A TWA is the average exposure over a specified period of time, usually a nominal eight hours. This means that, for limited periods, a worker may be exposed to concentrations higher than the PEL, so long as the average concentration over eight hours remains lower.
A short-term exposure limit is one that addresses the average exposure over a 15-30 minute period of maximum exposure during a single work shift. A ceiling limit is one that may not be exceeded for any period of time, and is applied to irritants and other materials that have immediate effects.
See also
- National Institute for Occupational Safety and HealthNational Institute for Occupational Safety and HealthThe National Institute for Occupational Safety and Health is the United States’ federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness. NIOSH is part of the Centers for Disease Control and Prevention within the U.S...
- Occupational Safety and Health AdministrationOccupational Safety and Health AdministrationThe United States Occupational Safety and Health Administration is an agency of the United States Department of Labor. It was created by Congress of the United States under the Occupational Safety and Health Act, signed by President Richard M. Nixon, on December 29, 1970...
- Recommended exposure limitRecommended Exposure LimitA recommended exposure limit is an occupational exposure limit that has been recommended by the United States National Institute for Occupational Safety and Health to the Occupational Safety and Health Administration for adoption as a permissible exposure limit...
External links
- OSHA Permissible Exposure Limits site (includes list of PEL values, and legal references)
- 1988 OSHA PEL Project Documentation: List by Chemical Name Available from NIOSH