They are available in green, yellow, and red smoke. Both white and colored smoke may be used for this purpose. Smoke signals are visible over greater distances when employed against a terrain background of contrasting color. Smoke is valuable for marking unit flanks, positions of lead elements, locations of targets, drop zones, tactical landing areas, and medical evacuation landing sites. Smoke signals are not suitable for messages, but are applicable when communicating by prearranged signals between small units and with aircraft.
Smoke grenades are available in white, green, yellow, red, and violet smoke.
This color range is provided by two types of grenades. When ignited, it produces dense white smoke for 105 to 150 seconds. It will not normally injure exposed troops. In heavy concentrations, troops should wear the field protective mask. However, the mask will not protect against heavy concentrations of this smoke in enclosed spaces due to oxygen depletion and carbon monoxide buildup.