GASP Alert: Allegheny County Board of Health Adopts Use of Continuous Opacity MonitorsEdit

On November 1, 2006, the Allegheny County Board of Health voted unanimously to adopt a regulation allowing the use of continuous opacity monitors (“COMs”) in air pollution enforcement. This measure modernizes the county’s monitoring of air pollution and allows regulators to ensure around-the-clock compliance with smokestack opacity limits. GASP would like to thank its members and friends who responded to our June 2006 call for comments supporting this important regulation. Thanks, in part, to numerous comments supporting the use of COMs the regulation passed with no appreciable opposition. Barring unexpected resistance from the County Council or Executive, the regulation will become effective before the end of the year.

Background Information: Opacity, in this context, refers to the percentage of light blocked by particles found in emissions. Therefore, opacity is a proxy measurement of the amount of harmful particles in smokestack plumes. Historically, opacity was measured by individuals trained to visually assess the transmittance of light through smoke plumes. This process is referred to as “smokereading.” Smokereading has its limitations, and foremost of these limitations is that it can only be conducted intermittently. Industrial facilities frequently operate and emit 24-hours a day, 7-days a week. At most, regulators are able to read opacity during daylight hours perhaps once a week. Therefore, opacity can be regulated using smokereading for only a small percentage of a facility’s operating time. Second, smokereading is subject to human error and is not as accurate as mechanical measurements. Smokereading remains useful as a measurement tool at facilities that do not have COMs installed and as a validation method.

Simply described, COMs equipment measures opacity electronically using light beams and light receptors. Light beams are shot across the interior of smokestacks between receptors. Those receptors are calibrated to continuously measure the amount of light passing through the plume. This process enables accurate, around-the-clock measurements of opacity; thus, regulators are able to ensure compliance with opacity regulations for 100% of a facility’s operating time.

The use of COMs has been permitted by the U.S. Environmental Protection Agency since 1997 via its “credible evidence rule” which allowed the use of all credible evidence in enforcement actions. The Board of Health’s vote today brings the county inline with this federal rule.

GASP was instrumental in initiating this regulation approximately two years ago. Walter Goldburg, a GASP Board Member, introduced the regulation in his capacity as a member of the Allegheny County Health Department’s Air Quality Program Regulation Subcommittee. GASP applauds this measure and looks forward to the public health benefits that should result from continuous, accurate enforcement of opacity regulations.

If you desire more information regarding this update, please contact Michael Parker, GASP’s Policy and Outreach Coordinator, via telephone at 412-325-7382 or e-mail at .


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