could experience irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape. AEGL-3 is the airborne concentration above which it is predicted that the general population, including susceptible individuals, could experience life-threatening health effects or death.”4

Adaptation The ability of some sensory receptors to modify the response to repeated or continued stimuli.1

AEGL See acute exposure guideline levels.

Aerosol A suspension of liquid or solid particles in a gas.5

Alveolar macrophage A mononuclear phagocytic cell arising from monocytic stem cells in bone marrow whose function is to ingest and digest foreign matter in the alveoli.1

Area under the curve (AUC) A measure of exposure that includes both duration and concentration. It is calculated from the curve that results when the concentrations of the test substance in some biologic tissue, typically blood, are plotted versus the exposure time.

ATSDR (Agency for Toxic Substances and Disease Registry) The ATSDR is an agency of the Department of Health and Human Services that was created by Congress under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), commonly known as the Superfund Act. Its mission is to serve the public by using the best science, taking responsive public health actions, and providing trusted health information to prevent harmful exposures and disease related to toxic substances. ATSDR defines minimal risk levels (MRLs).6

AUC See area under the curve.

CAMS See central atmosphere monitoring system.

CEGL See continuous exposure guidance level.


NRC (National Research Council). 2001. Standing Operating Procedures for Developing Acute Exposure Guideline Levels for Hazardous Chemicals. Washington, DC: National Academy Press.


Hawley, G.G. 1977. The Condensed Chemical Dictionary, 9th Ed. New York: Van Nostrand Reinhold Company.


See for more information.

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