disseminate the agent. If dissemination is by a weapon that releases the
agent directly on target, then Wind direction and speed have little
effect on the target coverage; however, downwind effects from the target
must be considered. If dissemination is by a weapon that releases the
agent upwind of a target area, then the wind must carry it to the target
Normally, the most effective wind speeds for effective target
coverage with a biological agent aerosol involving downwind travel are
from 8 to 18 knots.
d. Delayed Effect.
Biological agents do not cause casualties immediately. Time is required
for the agent to reproduce. After the microorganisms have multiplied in
sufficient quantity, they may overcome the body defenses and cause
There is a period of time from the time of entry of
microorganisms into individuals to the time they become sick or
This period of time-to-casualty, incubation period, is
typical for each agent and varies from a few days to a few weeks or
The particles of biological agent aerosols are so small and light that
they are carried by wind currents into dug-in positions, fortifications,
or other nonairtight shelters and structures. So-called hard targets for
other weapon systems would not be considered hard targets for biological
It is possible that the dose received inside a
nonairtight structure may exceed that received on the outside. This is
true because the structure, once penetrated, affords protection for the
agent, and it will probably persist for a much longer period of time.
Since biological agents, other than antimateriel agents, affect only
living things, equipment, facilities, and structures will be left intact
after a biological attack has occurred.
In addition, biological
explosive munitions usually utilize very low order explosives for
dissemination of the agent. Such explosions are not of sufficient force
to produce any significant destruction.
Spray weapon systems are
g. Difficult to Detect.
Biological agents that are disseminated as aerosols are not detectable by
any of the five physical senses--sight, smell, taste, touch, and hearing.
When someone comes in contact with such an aerosol, they inhale the
organisms without suspecting they have been the target of an attack.
Effects do not occur immediately, so the attack goes unnoticed. It is