CDC Health Advisory

Distributed via the Health Alert Network October 24, 2001, 22:30 EDT (10:30 PM EDT) CDCHAN-00045-01-10-24-ADV-N Many facilities in communities around the country have received anthrax threat letters. Most were empty envelopes; some have contained powdery substances. The purpose of these guidelines is to recommend procedures for handling such incidents.

Official CDC Health Advisory: CDC Interim* Recommendations for Protecting Mail Handlers from Cutaneous and Inhalational Anthrax Associated with Intentional Distribution of Bacillus anthracis through the Mail

As of October 24, 2001, the Centers for Disease Control and Prevention (CDC) is aware of five cases of inhalational anthrax among postal workers and mail handlers, including two fatal cases, as well as additional cases of cutaneous anthrax. These cases have been associated with exposure to mail contaminated with Bacillus anthracis. This document provides interim recommendations for protecting workers involved in mail sorting, distribution, and handling.

A program to reduce skin or respiratory exposures to B. anthracis spores may decrease the risk of anthrax disease in mail handlers. These interim recommendations are based on the limited information available on ways to avoid infection and the effectiveness of various prevention strategies. These recommendations will be updated as new information becomes available.

A hierarchy of measures should be used to control potential exposures to B. anthracis. These include, in hierarchical order, engineering controls to capture B. anthracis spores at potential points of release, housekeeping measures to reduce the spread of B. anthracis spores, and personal protective equipment to prevent worker exposure. The selection of these measures may be made after conducting a site-specific evaluation of the potential risk for B. anthracis exposure in each mail-handling facility. These recommendations should be incorporated into a comprehensive safety and health program for protecting mail handlers.

A major source of dust in mail handling facilities occurs during the operation and maintenance of high-speed mail handling machines. The "blowdown" of these machines in the maintenance operation can aerosolize particles in the size range of B. anthracis spores. Pinch roller operations should be evaluated for their potential to force dust-containing spores from envelopes.

The following recommendations are provided for workers potentially exposed to B. anthracis spores while handling or processing mail. These recommendations do not address instances where a known exposure has occurred. Mail facilities should develop an emergency plan to contain the hazards; this plan should be put into effect when a known or suspected exposure to B. anthracis occurs.

• Use an industrial vacuum cleaner equipped with a High-Efficiency Particulate Air (HEPA) filter as the first choice for cleaning high-speed mail-sorting equipment. If blowdown/blow-off must be used, first vacuum to remove as much dust as possible.
• Install engineering controls such as HEPA-filtered exhaust hoods for high-speed mail handling equipment and for other areas where dust is generated by processing mail. Local ventilation at pinch roller areas should be specifically considered.
• Install air curtains (using laminar air flow) to isolate areas where large amounts of mail are processed.
• Install HEPA filters in the building's HVAC systems to eliminate re-circulation of aerosolized spores.

• Avoid dry sweeping and dusting. Use wet cleaning and vacuuming. Use HEPA vacuum cleaners.

• A NIOSH-approved respirator at least as protective as a half mask respirator equipped with N100, P100, or R100 filters (disposable or elastomeric) should be used by any person who works with or near equipment or machinery known or suspected to generate aerosolized particles (e.g., electronic sorters) if dust levels cannot be or have not yet been adequately controlled by engineering controls. N100, R100, and P100 filters are at least 99.97% efficient at filtering out particles 0.3 microns in size when the respirator is properly fitted. Anthrax spores typically range from 2 to 6 microns in diameter.
• Half-mask respirators with P100 filters must be used in conditions where oil mist from machinery or high humidity is present.
• Fitted N95 respirators can be used by workers sorting mail in other areas, such as workers who hand-sort mail.
• Alternative respirators (such as powered air-purifying respirators with loose-fitting hoods) may be required for workers with facial hair (beards and or large moustaches) because facial hair interferes with the fit of protective respirators.