Individual protection increases from MOPP level 0, where only conventional protective equipment (web gear, helmet, and available flak vests) is worn and chemical-defense equipment is kept nearby, to MOPP level 4, where all protective equipment is worn. MOPP level Alpha requires individuals to only wear their mask and gloves and is used as a protective posture only in certain instances after the type of contamination has been determined.
As MOPP levels increase, an individual's efficiency decreases. Although less susceptible to being a chemical casualty, heat problems are more common. Noncommissioned Officers (NCOs) and Officers in the U.S. Military have been trained to ensure proper work and rest cycles for their "troops" are observed to control body heat buildup during CB warfare conditions. Dehydration is also a severe problem when people work in high temperatures while wearing the chemical-defense ensemble. People tend to drink to satisfy perceived thirst rather than to meet their actual physiological needs. Realizing this, the U.S. Military trains their personnel not wait to become thirsty before drinking. Military members are trained to drink regularly while in a MOPP to optimize their performance and to avoid becoming a heat casualty; and NCOs and Officers monitor and direct their people to drink the prescribed amount of water if they do not voluntarily drink enough (Note: the masks have a tube which can be used to drink from an attachment on the canteen lid, allowing military members to drink water in a contaminated environment).
MOPP Level 0. In MOPP Level 0, the mask is worn in a carrier on the military member's hip. Chemical-protective gear is issued, prepared, and located so the member can retrieve it within 5 minutes. MOPP Level 0 is used during periods of increased alert when the enemy has chemical/biological employment capability, but there is no indication of use in the immediate future.
MOPP Level 1.In this level, the chemical overgarment (pants and jacket) are worn, and the rest of the equipment is carried. MOPP Level 1 is used when it is determined that chemical/biological attack within the theater of operations is possible.
MOPP Level 2.In MOPP Level 2, the overgarment is worn, and the overboots are worn. The mask, hood and gloves are carried in the mask-carrier, strapped to the hip. MOPP Level 2 is initiated when chemical/biological attack is probable.
MOPP Level 3.In this MOPP level, the overgarment, mask/hood, and overboots are worn, but the protective gloves may be carried. MOPP Level 3 is used after chemicals have been used by the enemy, but in areas with negligible hazard.
MOPP Level 4. Everything is worn. This condition is used during/after an attack when chemical weapons have been used or are suspected.
MOPP Level Alpha.The mask, hood, and gloves are worn, but the protective overgarment is not. MOPP Level Alpha is called only during certain circumstances, such as when upwind from a negligible vapor hazard agent, or when inside buildings or aircraft.
Exposure to CB warfare agents may occur during and after an attack; therefore, U.S. Military personnel are trained to use extreme caution to limit the spread of contamination. Whenever possible, critical resources such as aircraft, vehicles, and equipment are protected from contamination by placing them under cover in hangars, sheds, or other structures, or covering them with plastic sheets or waterproof tarpaulins before a CB attack occurs. When sheltered in a building or tent, personnel are instructed to keep windows, doors, canopies, etc., closed when notified of a pending attack and after the attack until notified that the hazards no longer exist.
In addition to using protective clothing and equipment, common sense plays a large role when working in contaminated areas. Military personnel are trained to avoid kneeling, sitting, or walking in contaminated areas if possible, and not to touch anything unless it is absolutely necessary. When the mission permits, teams will be sent out to detect and mark contaminated areas. The U.S. Military has specialized chemical decontamination teams which can decontaminate equipment and land-areas, once the hazard has been identified and located.