Decon often is needed because avoidance is not always an option. By making it possible to lower MOPP level, decon supports protection. Combat power is restored and improved--certainly over what it would have been in full MOPP gear.
--FM 3-100, NBC Operations, 1985
Decontamination is not a difficult concept to understand. People that work with hazardous chemicals, in laboratories or in hospitals, understand that there is a risk of contamination by some foreign chemical or organism. First rule of lab safety is that one should be protected with adequate suits and masks, but one may require a process to clean off hazardous materials from personnel or equipment. The fastest way out of protective masks and suits is by verifying that you are clean of contamination, and you can either allow the weather to remove contamination (very slow) or accelerate the process with decontaminants. The $64,000 question becomes, how clean is clean?
As usual, the limiting factor was how well one could decontaminate chemical agents. Radiological particles and biological organisms could be washed off with soap and water, eliminating the threat to soldiers with the very low technology approach of hot water and soap. Non-persistent chemical agents, by their nature, are not around long enough to require decon operations. That led to persistent chemical agents such as mustard, thickened soman, and VX, which called for thorough decontamination processes during recovery and restoration phases to completely eliminate the threat.
The challenge is how much time and resources one has to pull troops and equipment off line to clean themselves up before they are thrown back into battle. No combat leader appreciates having less than 100 percent of his force on the line, but not being able to relieve the troops while they're in MOPP suits and dropping from heat stress is a sure recipe for disaster. As long as the unit is in MOPP gear, they are fighting at less than 100 percent and deteriorating quickly. If troops and equipment remain contaminated, they will spread it across clean areas of the