In-Depth Survey Report: Evaluation of Local Exhaust Ventilation Systems for the 010 Culling System at United States Postal Service, Merrifield Processing and Distribution Center, Merrifield, Virginia (June 2003)

摘要

Researchers from the National Institute for Occupational Safety and Health (NIOSH) conducted an evaluation of the Ventilation/Filtration System (VFS) developed for the United State Postal Service (USPS) mail processing equipment-the 010 Culling System. The VFS was developed and installed by a private contractor hired by the USPS to reduce the potential for employee exposure to harmful substances that could be contained in small pieces processed by the equipment. This effort is in response to the 2001 terrorist attacks that used the mail as a delivery system for anthrax. NIOSH was asked to assist the USPS in evaluating controls for this and other mail processing equipment. Evaluations were based on a variety of tests including: tracer gas (TG) experiments, air velocity measurements and smoke release observations to evaluate contaminant capture efficiency; and simultaneous particle count experiments upstream and downstream of the VFS filtration to evaluate system filtration efficiency. The experiments showed that, with few exceptions, the system meets or exceeds minimum contaminant capture requirements and that contaminant filtration capabilities meet or exceed 99.97%. However, testing did reveal poor contaminant capture efficiency at Flats Ejector No. (about 28%).