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July/August 2010

Plume Opacity

Air permits from regulatory agencies such as the U.S. Environmental Protection Agency often require the measurement of a plume’s opacity as the plume is emitted from a stationary point source (for example, smokestacks) in the outdoor ambient environment. While such opacity is often visually measured by human observers as “certified smoke readers,” an opacity measurement method using digital photography is now available as a new ASTM International standard.

D7520, Test Method for Determining the Opacity of a Plume in the Outdoor Ambient Atmosphere, was developed by Subcommittee D22.03 on Ambient Atmospheres and Source Emissions, part of ASTM International Committee D22 on Air Quality.

“This is a great story about how innovative technologies and techniques are developed with Department of Defense-supported research and they result in the development of new methods like D7520. The development of this new method to determine plume opacity with low-cost digital still cameras was initially described in peer-reviewed journals and conference proceedings and is now an approved ASTM standard to assist EPA in improving air quality at lower cost and with less subjectivity,” says Mark Rood, Ph.D., the Ivan Racheff professor of environmental engineering, University of Illinois, and a D22 member.


Technical Information: Mark J. Rood, Ph.D., University of Illinois,Urbana, Ill.

Phone: 217-333-6963

ASTM Staff: George Luciw

Phone: 610-832-9710