On March 6, 2002, USPS issued its Emergency Preparedness Plan. Without conducting tests that confirm the system’s ability to trap anthrax and not release any into the mail processing environment, the USPS has not proven that its design will meet the intent of protecting its employees and customers. USPS HEPA Design Calls for Additional Requirements

USPS believes that installing HEPA filtration systems will minimize the risks of airborne biohazards in the event of another anthrax attack, reduce dust levels, and lessen workers’ allergy-like symptoms. Therefore, USPS is proposing the use of HEPA filtration technology as a final filtering stage to remove smaller particles that constitute airborne biohazards. However, the design and configuration of the HEPA filtration system calls for additional requirements. Furthermore, USPS has not verified through testing that the HEPA air filtration system will not interfere with the air sampling and detection system. To ensure that USPS is making a sound investment, we recommend that the Postmaster General direct the Vice President of Engineering to complete the following actions before determining whether to proceed with a large-scale rollout of air filtration systems at 300 USPS P&DC/Fs: Perform tests to determine (1) the HEPA air filtration system’s ability to trap released hazards and other contaminants and (2) what level of hazards or contaminants could be released into the mail processing environment as a result of the air filtration system’s design. With regard to the concern about too much emphasis on secondary benefits, USPS noted that the main purpose of adding air filtration systems to the mail processing equipment is to minimize the potential exposure risk to postal employees and customers in the event of another anthrax attack. Postal Service
What GAO Found

Following the anthrax attacks of October 2001, the Unites States Postal Service (USPS) has started to look at various technologies that could be implemented in the event of another bioterror attack. The high-efficiency particulate air (HEPA) filtration system is being used as a prototype at two facilities and is planned for implementation throughout the country. HEPA filtering technology is the state-of-the-art technology for the removal of particulate biohazards and other particles of micron-sized range. USPS has not adequately tested the HEPA filtration system to confirm that it will meet its intended purpose of trapping anthrax spores and its secondary purpose of cleaning the mail processing equipment. USPS's testing has not shown conclusively (1) the HEPA filtration system's ability to trap released hazards and other contaminants, and (2) what level of hazards or contaminants could be released into the mail processing environment as a result of the air filtration system's design. Furthermore, USPS has not verified through testing that the air filtration system will not interfere with the air sampling and detection equipment. Even though HEPA filtration systems could reduce the risk of exposure to biohazards, they may negate the benefits of other technologies being considered by USPS to protect its employees and customers in the event of another anthrax attack. Finally, the design and installation of the HEPA filtration system requires custom modification to USPS equipment nationwide and will likely cost more than USPS projected in its Emergency Preparedness Plan.