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Engineering Controls Database

Postal Advanced Facer Cancellation System

In 2001, terrorist attacks took place where anthrax spores were sent by mail to a U.S. Senator and to media offices [CDC 2001]. These attacks resulted in exposure to anthrax spores by postal employees working in a mail processing facility that serves the U.S. Capitol and resulted in inhalation disease in several of the workers [Mayer et al. 2001].

One potential area of exposure in the United States Postal Service (USPS) is the automated mail processing equipment used to sort incoming mail. As the mail passes through the machinery, it is compressed and impacted in a number of places that could cause release of substances from the mail.
Bacillus anthracis is a large spore forming bacteria. In the vegetative state, it is rod shaped and ranges in size from 1-1.5 X 3-10 µm. The anthrax spores are typically in the 1-5 µm size range and can enter the body by being inhaled, through the skin, or through ingestion. Disease occurs when spores enter the body, germinate, and multiply. The cutaneous form of the disease generally develops 2-5 days following exposure and can usually be successfully treated with antibiotics. The onset for the inhalation form is typically l-6 days after exposure. The inhalation form generally has a high fatality rate even with appropriate treatment [Pile et al. 1998].
Researchers from the National Institute for Occupational Safety and Health (NIOSH) were requested to assist the USPS in the evaluation of particulate controls for various mail processing equipment. These new controls are being installed to reduce operator exposure to any potentially hazardous contaminants emitted from letter mail during normal mail processing. This effort is driven by the terrorist attacks which used the mail as a delivery system for anthrax.

There were a number of reports generated by NIOSH that evaluated controls put in place by the USPS to control release of contaminants into work areas of postal employees. This summary describes four reports that evaluated the capture effectiveness of the Ventilation/Filtration System (VFS) and the Biohazard Detection System (BDS) for the Advanced Facer Cancellation System (ACFS).
The AFCS is an automated mail-processing system that culls, orients, cancels, scans, and sorts standard size (5 to 11.5 inches long by 3.5 to 6.125 inches high) mailpieces. Mail is delivered to the AFCS from the 010 loose mail distribution system. The AFCS culls the mail to remove flats and overthick (greater than 0.25 inches) mailpieces. The mail is then properly oriented so it may be cancelled. Optical character recognition technology is used to read the addresses on the mailpiece which is then sorted and distributed to numbered bins for further automated processing.
The VFS for the AFCS consisted of an air/handling filtration unit that provided exhaust for locations of possible contaminant release. The air handling unit was fitted with three stages of filtration composed of a pre-filter, a Minimum Efficiency Reporting Value (MERV) 14 filter, and a High Efficiency Particulate Air (HEPA) filter. The effectiveness of the VFS was enhanced by enclosures put in place on the AFCS by the contractor. Hoods/enclosures were fitted around areas that have higher potential release from tainted mailpieces.

The BDS was designed to draw air from an area of the AFCS that would most likely contain a contaminant emitted from an envelope due to agitation or compression – the singulator area of the AFCS. The hood of the BDS is shaped like a tunnel and fits over the singulator area. In this area, the mailpieces are tightly compressed and abruptly accelerated in a process that caused them to move as individual pieces. The hood is approximately 4 inches wide by 5.5 inches high by 32 inches long. Air is drawn from the hood through a flexible duct into the detector which then analyzes the air for potential biohazard agents. If a hazard is detected, an alarm sounds and appropriate steps may be taken.
279-16A; 279-18A; 279-19A; 279-23A;
CDC (Centers for Disease Control and Prevention) [2001]. Investigation of bioterrorism-related anthrax and interim guidelines for exposure management and antimicrobial therapy. MMWR 50:909-919.

Mayer TA, Bersoff-Matcha S, Murphy C, Earls J, Harper S, Pauze D, Nguyen M, Rosentahal J, Cerva D, Druckenbrod G, Hanfling D, Fatteh N, Napoli A, Nayyar A, Berman EL [2001]. Clinical presentation of inhalation anthrax following bioterrorism exposure. JAMA 286(20): 2549-2553.

Pile JC, Malone JD, Eitzen EM, Friedlander AM [1998]. Anthrax as a potential biological warfare agent. Arch Intern Med 158:429-434.
automated facer cancellation system
engineering control
mail handlers
mail handlers
United States Postal Service
Evaluations were based on a variety of tests that involved tracer gas experiments, air velocity measurements, and smoke release observations. The experiments showed that generally, there was good capture by the VFS (96% or higher for most positions). When tracer gas was released around the BDS and BDS hood, capture efficiencies exceeded 98% for most positions and 90% for all positions. A number of recommendations were made by NIOSH to further improve the control of potential contaminants by the AFCS ventilation and filtration system.