In general, these measures closely parallel those provided for defense against chemical attack.
Since the inhalation of airborne organisms is considered to be the greatest potential hazard in biological warfare, the protective mask is an important component of defensive equipment. A mask that is in good condition and has been properly fitted will greatly reduce the possibility of inhaling infectious material in the air. Since the individual cannot detect the presence of biological agents, the use of the mask and other protective equipment will depend upon early warning.
To produce disease, biological agents must gain entrance into the body. A concentration of biological agents on the skin might, in time, be transferred to a portal of entry. Any type of clothing will provide some protection by reducing the quantity of agents coming in contact with the skin. The degree of protection afforded is dependent upon how well the fabric stops penetration and the number of layers of clothing being worn. Since this protective effect is due to the mechanical filtering or screening action of the cloth, it is important that shirt and jacket collars be fastened, sleeves rolled down and cuffs buttoned, trouser cuffs stuffed inside tops of boots or socks, and all other garment openings tied or otherwise secured to minimize the entry of airborne organisms and to reduce the risk of bodily contact with biological agents that may be present on the surface of the ground or in the air.
Military headgear helps safeguard the hair from heavy contamination, and ordinary gloves or mittens provide protection for the hands. The impregnated type of clothing issued for protection against chemical agents provides a higher degree of protection than the ordinary uniform, and whenever it is available it should be used.
Upon notification of an attack with biological agents, or before entering an area known to be contaminated by them, the individual will:
In biological as well as in chemical and radiological warfare, a tightly constructed shelter offers great protection. The shelter must be pressurized to prevent entrance of the microorganisms, which is accomplished by introducing filtered air into the shelter. If the shelter is reasonably tight, this incoming air will cause any flow of air to be outward. Any building, shelter, or field fortification without this feature provides only limited protection from aerosols. Eventually microorganisms will penetrate through cracks and will constitute a respiratory hazard unless the protective mask is worn. Again, utilization of shelters will depend upon early warning.
Food and water supplies are especially susceptible to deliberate contamination. Civilian supplies all too frequently do not receive careful supervision and protection and must always be suspected of accidental or deliberate contamination. It should also be emphasized that water is not necessarily pure just because it comes from a faucet. In some countries pure water is the exception rather than the rule. The safest rule is to consume only foods and drinks received from military sources. Procedures for protection of the water supply and routines for inspection and decontamination are well defined in the military and, if diligently observed, will protect from deliberate contamination.
Chlorination is by far the almost universal method of purifying water, and it destroys most of the biological agents. Boiling maybe required to ensure proper decontamination in exceptional cases.
The military establishes water points in the field whenever possible. The equipment location at these points provides for filtration as well as chlorination and, when properly operated, is effective in removing organisms that produce disease. Some biological agents cannot be destroyed by normal water purification techniques. When biological agents are known to have been used, all drinking water must be boiled. In