Leaders often are the first MOPP casualties. Unit movement formations bunch up to help leaders maintain control. It takes twice as long to complete an attack, and nearly twice as many soldiers are required for success. Weapon crews use terrain much less effectively for cover and concealment, and the number of casualties suffered per enemy defender killed increases by 75 percent. Shots fired at friendly instead of enemy soldiers increases from 5 to almost 20 percent.
Indirect fire becomes more effective than individual weapons in inflicting casualties on the enemy.
Total time spent on radio traffic more than doubles. The number and length of radio transmissions rises by 50 percent. Depending on the tactical situation, commanders choose the appropriate MOPP level. Physical demands of the projected work Mental demands of the projected work Speed required for mission accomplishment Expected duration of the mission Likely follow-on mission Whether adequate water and food supplies are available Commanders must also consider other factors when setting the MOPP level. For example, the most likely time for a chemical attack is between late evening and early morning, when agent vapor tends to linger close to the ground.