As facilities throughout the U.S. receive anthrax threat letters - whether they're false alarms or contain actual biological agents - the Center for Disease Controls (CDC) has issued an official health advisory, which provides procedures for handling such incidents.

1. Do not panic Anthrax organisms can cause infection in the skin, gastrointestinal system or the lungs. To do so, the organism must be rubbed into abraded skin, swallowed or inhaled as a fine, aerosolized mist. Disease can be prevented after exposure to the anthrax spores by early treatment with the appropriate antibiotics. Anthrax is not spread from one person to another.

2. Identify the suspicious letter or package Some characteristics of suspicious packages and letters include: excessive postage; handwritten or poorly typed addresses; incorrect titles; a title, but no name; misspellings; stains, discolorations or odor; no return address; excessive weight; lopsided or uneven envelope; excessive security material such as masking tape, string, etc.; ticking sound; restrictive markings such as "Personal" or "Confidential"; city or state in the postmark that does not match the return address.

3. Get away from the letter or package Do not shake or empty its contents. Place the letter or package in a plastic bag or other container to prevent the contents from leaking, or cover the envelope or package with some sort of paper or a trash can. Likewise, if powder from an envelope spills onto a surface, do not try to clean it up. Instead, cover the spilled contents immediately, leave the room, close the door and prevent others from entering. Wash your hands with soap and water.

4. Report the incident to local police Besides reporting the incident to police, notify your building security official or an available supervisor. List all people who were in the room or area when the letter or package was recognized.

5. Remove contaminated clothing Remove clothing as soon as possible and place it in a plastic bag or some other sealable container. Give the clothing container to emergency responders for proper handling.

6. Shower with soap and water Do this as quickly as possible. Do not use bleach or other disinfectant on your skin.

7. Beware of room contamination by aerosolization If warning is given that the air handling system is contaminated or that a biological agent has been released in a public space, turn off local fans or ventilation units in the area and leave the area immediately. Close the door or section off the area to prevent others from entering. Notify authorities and shut down the air handling system in the building, if possible. List all people who were in the room or area.