III. OPERATIONAL USE AND LIMITATIONS
A. CPE Wear Time
CPE components are rated for how long they provide full protection in both contaminated and non-contaminated environments. For example, in a contaminated environment, the Chemical Protective Overgarment (CPOG) is rated for up to six hours of protection and the Battledress Overgarment (BDO) for 24 hours. Overgarments actually exposed to chemical warfare agents are never worn again.
In a non-contaminated environment, the CPOG gradually begins to lose protection after 14 days of almost full time wear, while the BDO can last 30 days. Returning the garments to their vapor-seal bags "stops the clock" on these wear periods. The bag protects the overgarment from the degrading effects of such things as moisture, smoke, fuel solvent vapors, and sunlight. Over time, extensively worn overgarments can also become unserviceable because the charcoal migrates to the end of the sleeves and trousers, or the knees and elbows wear out, or the garment is exposed to too much mud and dirt. Because of the limited availability in the Gulf of replacement CPE, commands were flexible about wear time in a non-contaminated environment under CW threat. It was decided that wearing an overgarment beyond the established full protection limits would put troops at less risk than being exposed to chemical warfare agents without sufficient replacement protective gear.
B. Performance Degradation Caused by CPE Wear
Depending on the outside temperature and the physical level of work, MOPP postures above Level 0 can result in the following individual performance limitations:
In recent years, the impacts of these kinds of effects (at MOPP Level 4) on combat operations have been studied extensively in Army field exercises. The following is a compendium of observations taken from reports on these studies:
- In a variety of tasks, degradation is 20 to 50 percent.
- Oxygen consumption increases about 10 percent in full CPE compared to light clothes. This indicates that personnel in MOPP-4 expend more energy than personnel in MOPP-0 performing the same tasks.
- Reduced sensory awareness makes it harder to stay awake when tired.
- Soldiers require 1.5 to 3 times longer to perform tasks requiring manual dexterity in MOPP-4 than without CPE.
- Performing a task for the first time takes about 30 percent longer.
- Troops tend to omit or poorly complete certain tasks (such as camouflage and support activities).
- Some cognitive tasks, like encoding, suffer a performance loss of nearly 23 percent in MOPP-4.
- Leader performance declines: they become exhausted, sleep less, become disoriented or lost, get irritable, and delegate less. Leaders often are the first MOPP casualties.
- Unit movement formations bunch up to help leaders maintain control.
- When platoon leaders become casualties, it takes four times as long for a platoon to realize it is leaderless. The next senior soldier assumes command 85% less often than in non-CPE exercises.
- NBC Overboots provide poor footing on hilly terrain, on loose ground, or in rain.
- NBC garments absorb rain and become very heavy and cumbersome.
- Rifle marksmanship drops about 15 to 19 percent for soldiers in MOPP-4.
- Individual weapon firing rates decrease 20 percent in the defense and 40 percent in the attack. It takes twice as long to complete an attack, and nearly twice as many soldiers are required for success.
- The proportion of enemy personnel engaged decreases by one-third.
- 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.
- Platoons call for three times more indirect fire (e.g., artillery). Indirect fire becomes more effective than individual weapons in inflicting casualties on the enemy.
- Land navigation is seriously degraded, particularly at night.
- Night vision devices cannot be used while masked.
- Radio communication is difficult because of reduced clarity and volume. Speaking through the voicemitter makes the speaker sound brassy and muffled, and consonants become indistinct. The hood and background noise (breathing, garment movement, etc.) degrades hearing.
- Communications are only about half as effective as in a non-CPE environment. Total time spent on radio traffic more than doubles. The number and length of radio transmissions rises by 50 percent.
- Logistics operations take longer and can become confused.
- Maintenance takes longer. Recovering armored vehicles takes up to 20 percent more time; repairing weapons takes up to 70 percent more time.
Training for key combat tasks in CPE can reduce such performance degradation.
C. MOPP Level Analysis
Depending on the tactical situation, commanders choose the appropriate MOPP level. Before making a decision, the commander must address the following issues: 
- Nature of the mission (offensive or defensive)
- Likelihood of CW use and what agents might be used
- Likely friendly targets
- Expected warning time
- Additional available protection (shelter or cover)
- 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. In the heat of the day, agents rise rapidly in unstable air.
D. Commanders Guidance
Commanders should use MOPP flexibly to protect their forces in a potential or actual Chemical Warfare situation. While the various headquarters provide initial directives on MOPP level, subordinate units often adapt this guidance to local conditions when warranted (although a commander generally sets a minimum MOPP level). Units can increase the MOPP level set by higher headquarters in response to direct threats.
Because Gulf War commanders often had to use their own judgment in setting MOPP levels, different units experienced different degrees of CPE wear under similar circumstances. For example, after the first 24 hours of the ground war, the commander of the 2d Marine Division had his forces take off their CPE. In the adjacent 1st Marine Division sector, Marines continued to wear some of their CPE throughout the ground offensive.
E. Reducing MOPP Level and Unmasking
Commanders downgrade the MOPP level as the threat decreases. Before a unit unmasks in a potential chemical threat area, the units chemical detection equipment must determine if a chemical hazard exists. If such tests are negative, the next step is "selective unmasking." Figure 4 diagrams the process.
Figure 4. Selective Unmasking Process
The M256 kit is the most sensitive vapor detection gear. If a unit must use a less sensitive test for an initial contamination check, full unit unmasking requires at least two limited unmaskings to confirm no contamination. First, one or two designated troops hold their breath, unmask for 15 seconds with their eyes open, and then remask. Others then observe their eyes for contraction of the pupils (miosis), the first sign of exposure to nerve agent vapor. If those who unmasked show no symptoms, they remove their masks and breathe normally for five minutes and remask while being observed for symptoms. If no symptoms appear, an all clear is sounded and the remaining troops of the unit unmask. When the sensitive M256 kit confirms no contamination, the procedure skips the first step involving eye exposure without breathing. All selective unmasking involves careful observation of the designated troops and immediate readiness to administer antidotes in response to any sign of toxic reaction.
Procedures established for some Army units in the Gulf included an extra selective unmasking step after unmasking for 15 seconds without breathing. This step, used where no detection equipment was available, involved unmasking and taking two or three breaths and remasking for an additional 10 minutes of observation. If no symptoms appeared, the same soldiers unmasked for five minutes.
F. Automatic Masking
In addition to establishing the MOPP Level, commanders set the guidance for automatic masking. Automatic masking means that no matter what the command-established MOPP Level, military personnel are expected to rapidly don masks if there is an immediate threat. For example, automatic masking could occur under any of the following conditions:
- An automatic chemical agent alarm sounds.
- A chemical agent detector paper reads positive.
- Troops experience symptoms of a chemical agent exposure.
G. Threat Level Color Codes
Some US Air Force and Marine units in Operation Desert Storm used color codes to supplement MOPP levels. These codes generally referred to the immediacy of the chemical threat. The Marines system included the following:
- "White." Enemy forces have the capability to employ NBC weapons, but attack is not probable at this time.
- "Yellow." Attack probable, units maintain MOPP-0.
- "Red." Siren sounds. Attack is imminent. Units go to MOPP-4.
- "Black." Siren sounds. Friendly forces nearby have been attacked with CW. Units remain in MOPP-4 until "all clear" is given.
The Air Force had a similar system, with stages defined differently:
- "All Clear." Normal Operations. Have Chemical Protective Equipment (CPE) and field gear readily available.
- "Alert Yellow." Attack is probable. Wear CPE and field gear as directed.
- "Alert Red." Attack is imminent or in progress. Don protective equipment (to include field gear) and take cover.
- "Alert Black." NBC contamination is suspected or actual. Wear full chemical protective ensemble and field gear.
An Air Force daily log for Al Kharj Air Force Base, Saudi Arabia included this entry for January 21,1991:
"At 2200 hours the air base went on a Red Alert, MOP[P] Level IV. Personnel were warned to take cover but the alert was called off after a short period of time. Al Kharj Air Base was then put on a Yellow Alert, MOP[P] Level II which meant that people, for the second time in three nights, had to sleep in their chemical warfare gear."
In late January, after SCUD missile attacks failed to include chemical warheads (and a need to conserve scarce overgarments became clear), the Air Force instituted MOPP Level ALPHA. This involved taking cover in a hallway or bunker, donning the mask, hood, and gloves, and ensuring full body coverage with long pants and long-sleeved shirts; no NBC overgarments were donned. If an attack actually ensued, ALARM BLACK MOPP ALPHA was to be declared. The overgarments, however, were to be left packed and at hand unless a chemical agent was actually detected. In that event, ALARM BLACK MOPP 4 would be issued and the overgarments would be donned.
Despite these variations, the standard MOPP level system was the primary way of tying protection level to chemical agent threat for the majority of US forces during the Gulf War.
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