YELLOW ZONE: Anthrax Matrix Pyramid Yellow Zone Workplaces Where Contamination with Anthrax Spores Is Possible
This zone is where workplace contamination is possible. Risk factors that should be considered in this zone include handling bulk mail, handling mail from facilities that are known to be contaminated, working near equipment such as high-speed processors/sorters that could aerosolize anthrax spores; workplaces in close proximity to other workplaces known to be contaminated; or workplaces that may be targets of bio-terrorists.

Engineering controls are the most effective controls an employer can use to protect employees. The Centers for Disease Controls and Prevention (CDC) provide a list of suggested engineering controls in Recommendations for Protecting Workers from Exposure to Bacillus anthracis in Work Sites Where Mail Is Handled or Processed.

Prudent Work Practices:

  • Follow OSHA's recommendations for green zone workplaces for workers who open mail or respond to suspicious envelopes or packages.
  • Develop strategies to limit the number of persons working at or near areas where airborne particles may be generated (e.g., mail-sorting machinery, places where mailbags are unloaded or emptied).
  • Restrict the number of non-essential personnel (e.g., contractors, visitors, etc.) entering areas where airborne particles may be generated.
  • Avoid practices that generate dust, such as dry sweeping, dusting, and using compressed air to clean machinery. Areas should be wet-cleaned or vacuumed with an industrial vacuum cleaner equipped with a high-efficiency particulate air (HEPA) filter. Conventional home or industrial vacuums should not be used since these vacuums may further disperse possible anthrax spores.
  • Instruct employees to wash hands regularly with soap and water. At a minimum, hands should be washed when gloves are removed, before eating, and at the end of a shift.
  • Establish procedures in the emergency plan for employees to report possible exposure and contact authorities:
    • Contact supervisor
    • Notify local police and local FBI
  • Give workers information and training on:
    • Modes of anthrax transmission;
    • Signs and symptoms of anthrax infection;
    • Emergency procedures to deal with possible contamination;
    • Protective clothing to minimize skin exposure;
    • Care for abrasions that might provide an infection route.
Personal Protective Equipment (Voluntary)
  • Impermeable gloves such as nitrile or vinyl.
  • Properly fitted, NIOSH-certified filtering facepiece (N95 or greater). See Appendix D of OSHA's Respiratory Protection standard for information about the use of respirators when such use is voluntary. 29 CFR 1910.134 Appendix D
  • Respirators equipped with P-type filters in areas where oil mist from machinery is present should be considered to ensure filter effectiveness.
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