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In-depth survey report: evaluation of local exhaust ventilation system for advanced flat sorter machine at United States Postal Service, Baltimore Processing and Distribution Center, Baltimore, Maryland.

Topmiller JL; Crouch KG; Beamer B; Shulman SA
Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, EPHB 279-12a, 2002 Jul; :1-15
Researchers from the National Institute for Occupational Safety and Health (NIOSH) conducted evaluations of an exhaust ventilation system developed for the Automated Flat Sorting Machine (AFSM) 100. This system was installed by the machines manufacturer to reduce the potential for employee exposure to harmful substances that could be contained in mailpieces processed by the machine. This effort is in response to recent terrorist attacks that used the mail as a delivery system for anthrax. NIOSH was asked to assist the United States Postal Service (USPS) in evaluating controls for this and other mail processing machinery. Evaluations were based on a variety of tests including tracer gas experiments, air velocity measurements, smoke release observations, and particle count experiments. The experiments showed that, overall, there is good capture by the exhaust ventilation system. Tracer gas tests indicated that the capture was essentially 100% between the feed table and the bucket insertion point. At the bucket insertion point, the measured capture efficiency was approximately 81%. The exhaust ventilation system also exhibited good capture characteristics based on smoke release experiments and air velocity measurements. Particle count measurements were inconclusive. It was determined that this method does not produce repeatable enough results for use in this situation. Based on these results and others discussed in this report, the following recommendations are suggested: 1. Consider adding a ventilated partial enclosure at the point where the mailpieces enter the moving buckets to reduce the potential for contaminant release; 2. Seal cooling fan openings for fans that have been disconnected. These openings allow for the potential release of a substance that has been captured; 3. Consider more thoroughly evaluating the capabilities of the exhaust system with additional smoke and tracer gas testing, particularly after changes are made to the ventilation and filtration system. The tested system only had ventilation on one of the three feeders, and HEPA filters were not installed on the filtration unit.
Region-3; Postal-employees; Engineering-controls; Equipment-design; Equipment-reliability; Control-technology; Biological-warfare-agents; Biological-weapons
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Field Studies; Control Technology
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National Institute for Occupational Safety and Health
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division