Contamination is the introduction of microorganisms into tissues or sterile materials. Decontamination is disinfection or sterilization of infected articles to make them suitable for use (the reduction of microorganisms to an acceptable level). Disinfection is the selective elimination of certain undesirable microorganisms in order to prevent their transmission (the reduction of the number of infectious organisms below the level necessary to cause infection). Sterilization is the complete killing of all organisms. BW agents can be decontaminated by mechanical, chemical and physical methods.

Decontamination methods have always played an important role in the control of infectious diseases. However, we are often unable use the most efficient means of rendering infectious diseases harmless (e.g., toxic chemical sterilization) in order to not hurt people or damage materials which are to be freed from contamination.

Mechanical decontamination involves measures to remove but not necessarily neutralize an agent. An example is the filtering of drinking water to remove certain agents (e.g., Vibrio cholera or Clostridium botulinum) that may have been used to purposefully contaminate a water supply.

Chemical decontamination renders BW agents harmless by the use of disinfectants which are usually in the form of a liquid, gas or aerosol. One has to remember that some disinfectants are harmful to humans, animals, the environment, and/or materials.

Dermal exposure with a suspected BW agent should be immediately treated by soap and water decontamination. Careful washing with soap and water removes a very large amount of the agent from the skin surface. It is important to use a brush to ensure mechanical loosening from the skin surface structures, and then rinse with copious amounts of water. This method is often sufficient to avert contact infection. The contaminated areas should then be washed with a 0.5% sodium hypochlorite solution, if available, with a contact time of 10 to 15 minutes.

Ampules of calcium hypochlorite (HTH) are also currently fielded in the Chemical Agent Decon Set for mixing hypochlorite solutions. The 0.5% solution can be made by adding one 6-ounce container of calcium hypochlorite to five gallons of water. The 5% solution can be made by adding eight 6-ounce ampules of calcium hypochlorite to five gallons of water. These solutions evaporate quickly at high temperatures so if they are made in advance they should be stored in closed containers. Also the chlorine solutions should be placed in distinctly marked containers because it is very difficult to tell the difference between the 5% chlorine solution and the 0.5% solution.

To mix a 0.5% sodium hypochlorite solution, take one part Clorox and nine parts water (1:9) since standard stock Clorox is a 5.25% sodium hypochlorite solution. The solution is then applied with a cloth or swab. The solution should be made fresh daily with the pH in the alkaline range.

Chlorine solution must NOT be used in patients with (1) open abdominal wounds, as it may lead to the formation of adhesions, or (2) brain and spinal cord injuries. However, this solution may be instilled into non-cavity wounds and then removed by suction to an appropriate disposal container. Within about 5 minutes, this contaminated solution will be neutralized and nonhazardous. Subsequent irrigation with saline or other surgical solutions should be performed. Prevent the chlorine solution from being sprayed into the eyes, as corneal opacities may result.

For decontamination of fabric clothing or equipment, a 5% hypochlorite solution should be used. For decontamination of equipment, a contact time of 30 minutes prior to normal cleaning is required. This is corrosive to most metals and injurious to most fabrics, so rinse thoroughly and oil metal surfaces after completion.

BW agents can be rendered harmless through such physical means as heat and radiation. To render agents completely harmless, sterilize with dry heat for two hours at 160 degrees centigrade. If autoclaving with steam at 121 degrees centigrade and 1 atmosphere of overpressure (15 pounds per square inch), the time may be reduced to 20 minutes, depending on volume. Solar ultraviolet radiation (UV radiation) has a certain disinfectant effect, often in combination with drying. This is effective in certain environmental conditions but hard to standardize for practical usage for decontamination purposes.

Rooms in fixed spaces are best decontaminated with gases or liquids in aerosol form (e.g., formaldehyde). This is usually combined with surface disinfectants to ensure complete decontamination. Environmental decontamination of terrain is costly and difficult and should be avoided, if possible. If contaminated terrain, streets, or roads must be passed, spray with a dust-binding spray to minimize reaerosolization. If it is necessary to decontaminate these surfaces, chlorine-calcium or lye may be used. Otherwise, rely on the natural processes which, especially outdoors, leads to the decontamination of agent by means of drying and solar UV radiation.