The threat is effective. You force the enemy to carry extra gear for protection and decontamination. With a serious immediate threat, you can force the enemy t

The threat is effective. You force the enemy to carry extra gear for protection and decontamination. With a serious immediate threat, you can force the enemy to wear the full NBC gear. That impedes everything. They can't effectively eat or wash, their vision is restricted, and they might get heatstroke.