Development of evaluation procedures for local exhaust ventilation for United States Postal Service mail processing machinery.
Beamer-B; Crouch-K; Topmiller-J
American Industrial Hygiene Conference and Exposition, May 10-15, 2003, Dallas, Texas. Fairfax, VA: American Industrial Hygiene Association, 2003 May; :48
National Institute for Occupational Safety and Health researchers have conducted engineering evaluations of new local exhaust ventilation systems installed on United States Postal Service automated mail sorting equipment by independent contractors. The local exhaust ventilation systems have been developed primarily as a partial response to the use of mail to transmit anthrax, and the resulting infection of postal employees. We describe here the development of a testing protocol to determine the effectiveness of the ventilation systems in containing potential emissions from mail during processing by the sorters. The protocol specifies the use of air velocity measurements and smoke release observations where mail emissions could escape to the workroom environment. Also, the protocol includes measurement of the capture efficiency of the local exhaust ventilation for potential emissions from the mail, using a tracer gas technique. The approach was useful in locating the few areas needing improvement, and in establishing the generally high (>98%) control efficiency of the installed local exhaust ventilation. The absolute error in determining the capture efficiency was less than 2% using this technique. Changes to the ventilation system, such as volumetric flow rate adjustments, could be evaluated relatively quickly, and with a high degree of confidence, based in part on a real-time display of the tracer gas capture efficiency, and on the visual evidence provided by smoke release. Time-dependent effects, such as the clearance rate of an instantaneous airborne release, could be observed easily and quantitatively using this protocol.
Exhaust-systems; Exhaust-ventilation; Occupational-safety-programs; Safety-measures; Work-environment; Postal-employees; Ventilation-systems; Biohazards; Biological-weapons; Chemical-warfare-agents; Biological-warfare-agents
American Industrial Hygiene Conference and Exposition, May 10-15, 2003, Dallas, Texas