TWA 11 : Time-Weighted Average exposure. The airborne concentration of a material to which a person is exposed, averaged over the total exposure time, generally over a total workday period of 8 hours. See also TLV
Environmental Health & Safety, Glossary of Common Laboratory Safety and Hygiene Terms, Columbia University in the City of New York, USA 2008. http://ehs.columbia.edu/Glossary.html, (Lab Sfty and Hyg - Amer) {57}