The Occupational Safety and Health Administration (OSHA) created a model to help businesses deal with the threat of anthrax in the workplace. OSHA's "anthrax matrix" is designed to help employers assess the risk of anthrax contamination and specifies safe work practices for businesses at low, medium and high risk. However, the agency stressed that its guidance does not impose new requirements on employers.
The matrix is shaped like a pyramid with three sections: green for low, yellow for medium and red for high risk. Each section is linked to guidance to help employers determine appropriate responses to the risk.
The green zone. The vast majority of U.S. workplaces fall in the green zone, according to OSHA. The agency recommends that employees in these low-risk businesses should be on the lookout for suspicious mail and not open it. Procedures on dealing with suspicious mail include the recommendations to not handle it any further after identifying it as suspicious, to not clean up any suspicious substances and to contact the appropriate authorities.
In general, employees in green-zone businesses should open mail with a letter opener and not blow into it. While opening mail, employees should keep their hands away from their noses and mouths, and not run fans. They should wash their hands after handling mail, OSHA said.
The yellow zone. Workplaces in the yellow zone that face medium levels of risk include those that handle bulk mail, handle mail from facilities know to have been contaminated, are located near contaminated workplaces and are potential targets of bio-terrorism.
OSHA suggests that workers in these businesses should follow the green-zone procedures listed above, and limit the number of people in areas where airborne particles could be generated, give workers training on anthrax and establish an emergency plan for employees to report possible exposure. Where high-speed mail sorting equipment is in use, OSHA recommends that businesses use an industrial vacuum cleaner with a high-efficiency particulate air (HEPA) filter to clean the machines, and use HEPA filters in other areas, including in the ventilation system.
The red zone. OSHA defined high-risk, red-zone businesses as those that authorities have identified as suspected or confirmed to be contaminated, and businesses that are engaged in the clean-up of bioterrorist anthrax. Emergency response, investigation and clean-up require highly specialized methods and should be conducted under OSHA's Hazardous Waste Operations and Emergency and Response Standard (HAZWOPER).