Glossary of Terms: H

Hazardous areas
Areas where there is the possibility of the presence of an explosive mixture of flammable gas or vapor and air are known as ‘Hazardous’ and other areas as ‘safe’ or ‘non-hazardous’. Any electrical equipment used in hazardous areas must be tested and approved to ensure that, in use even under fault conditions, it cannot cause an explosion.
Hazardous material
Any substance that may produce adverse health and/or safety effects to people or the environment.
Hearing conservation (HC)
The Occupational Safety and Health Administration (OSHA) and Mine Safety and Health Administration (MSHA) provide regulatory standards for hearing conservation programs. In addition, the American Conference of Governmental Industrial Hygienists (ACGIH) provides industrial standards for hearing conservation programs
Heat exhaustion
Overheating of the body. Heat exhaustion can happen when the body loses too much fluid (because of excessive sweating) or when conditions, such as
Heat stroke
A potentially deadly condition in which over-exposure to a very hot environment breaks down the body’s ability to control its temperature and cool itself sufficiently. The body temperature rises to a very high (deadly) level.
HEPA filter
High efficiency particulate air filter. A disposable, extended medium, dry type filter with a particle removal efficiency of no less than 99.97 percent for 0.3m particles.
Hertz (Hz)
Unit of vibration frequency in cycles per second.
Hood entry loss
The pressure loss from turbulence and friction as air enters the system
Hood static pressure
Suction or static pressure available in the duct behind the hood to draw air into the hood
Strategically positioned devices designed to enclose or capture process contaminants
A way of controlling hazards along the path between the source and the worker. Good housekeeping means having no unnecessary items in the workplace and keeping all necessary items in their proper places. It includes proper cleaning, control of dust, disposal of wastes, clean-up of spills and maintaining clear aisles, exits, and work areas.
Human error
Workers’ errors or the engineering deficiencies and lack of adequate organizational controls which together account for the majority of accidents.
The condition of being reactive to substances that normally would not affect most people.
A condition in which body temperature drops below normal (36°C or 96.8°F). It most frequently develops from being exposed to very low temperatures. Hypothermia can cause death.