Glossary of Terms
Acquired Immunity: is gaining the ability to prevent a particular infection. Immunity can be acquired by receiving a vaccination, or getting a disease once and then the body’s immune system prevents further infection to that disease.
Boiling Point: the temperature at which a liquid will boil or change to a gas. The lower the boiling point, the faster it will evaporate into the air.
Carcinogen: an agent that causes cancer.
CAS Number: the identification number given to a chemical by the Chemical Abstracts Service (CAS).
Ceiling Limit: the maximum level of exposure to a toxic agent that is allowed at any time.
Communicable Disease: An infectious disease that can be spread from person to person or animals to humans.
Confined Space: an area with a small opening that is large enough for someone to enter and work.
Decibel (dB): the unit that is used to measure sound.
Ergonomics: the practice of changing the work environment to meet the physical and other needs of workers.
Flash Point: the lowest temperature at which a chemical vapor will light on fire.
Fumes: are solid particles that are formed when a substance that has evaporated condenses in cool air. Fumes often result as molten metals cool.
Gases: are fluids that have no shape and expand to fill the shape of the space in which they are contained.
Hierarchy of Controls: a term that refers to using the most effective means possible to control hazards. The order of effectiveness to control hazards is: using a different product or process (substitution), isolating the hazard, removing the hazard with equipment (engineering controls), using ergonomics, changing the way work is organized (administrative controls), using personal protective equipment.
High-Efficiency Particulate Air (HEPA): a filter for respirators, vacuum cleaners, and other products that can trap extremely small particles, fibers and germs. HEPA filters are used to prevent breathing asbestos, lead, tuberculosis.
Imminent Danger: a situation that poses an immediate threat of death or serious injury or illness.
Ionizing Radiation: a form of physical energy that moves in wave-like motion and includes alpha, beta and X-rays. Ionizing radiation is powerful enough to change an atom’s structure and can kill living cells and cause cancer, sterility and birth defects.
Mists: droplets of a liquid that are suspended in the air.
Material Safety Data Sheet (MSDS): a form containing information on a chemical. Employers must have an MSDS available to workers for each hazardous chemical used in the workplace under OSHA’s Hazard Communication Standard(29 CFR 1910.1200).
Mutagen: an agent that can change the genetic make-up of a cell. Mutagens can cause cancer, miscarriages and unwanted inherited traits.
Non-Ionizing Radiation: physical energy that moves in wave-like motion that does not change the structure of atoms.
Particulate: a particle of a solid or liquid that is suspended in the air.
Parts Per Million (ppm): a unit that is used to measure the concentration of a substance in a given area. Chemical exposures are usually given as the number of molecules of a chemical within a million molecules of air. One part per million is equal to one drop of water in 18 gallons of water, or one inch in 16 miles.
Permissible Exposure Limit (PEL): the legal level of exposure to a substance that is allowed by OSHA.
Reactivity: refers to how easily a substance will undergo a chemical change that can have a dangerous effect such as an explosion.
Recommended Exposure Limit (REL): a level of exposure that is set by the National Institute for Occupational Safety and Health.
Reproductive Effects: exposure of men or women to agents that results in infertility, impotence, loss of sex drive and birth defects.
Sensitizer: an agent that can cause an allergic reaction. Common sensitizers include formaldehyde and latex.
Short-Term Exposure Limit (STEL): the level of exposure that is allowed for a short period of time, up to 15 minutes. Certain OSHA standards have STELS.
Specific Gravity: the weight of a substance compared to air or water. A gas that is heavier than air (more than 1.0) will sink.
Susceptible Host: a person or animal that can be infected by a particular communicable disease.
Teratogen: a substance that causes birth defects.
Threshold Limit Value (TLV): a level of exposure set by the American Conference of Governmental Industrial Hygienists.
Time-Weighted Average (TWA): the level of exposure that is allowed based upon a full work shift of 8 hours.
Vapor Density: is the weight of a vapor compared to air. A vapor that is lighter than air (less than 1.0) will rise into the air.
