What Is The Army MOPP Gear And What Does MOPP Level 4 Mean

To defend the home front, mankind has been developing technologies that have resulted in the most significant number of enemy casualties for hundreds of years. 

The strategies military leaders employ to instill terror in the minds of their deadly opponents change with time. One such classic threat is the possibility of a chemical attack, which can occur instantly and kill anybody in its path.

Although most of the world community now despises chemical strikes, they were used on the front lines of World War I, and they are still a threat. U.S. forces are more trained than ever to defend themselves from potential threats by employing specialized equipment.

Mission Oriented Protective Posture (MOPP) gear is provided to safeguard our men from chemical, biological, radiological, and even nuclear attacks

What is MOPP?

What Is The Army MOPP Gear And What Does MOPP Level 4 Mean

With MOPP, missions can be completed more efficiently by providing adaptable chemical agent protection. 

MOPP is a catch-all term that can refer (usually speaking) to the current protective posture required, as well as to the usage of MOPP gear in general and occasionally even to the gear itself.

The presence or absence of NBC threats is the first factor to consider—do troops need to wear the equipment and adopt the protective postures?—because this equipment and the accompanying use levels are designed to protect against NBC threats. 

If not, why not? In the face of NBC threats, commanders must deal with these issues.

The majority gain knowledge of this during basic training, where recruits are frequently instructed on how to quickly wear MOPP gear, which includes protective coveralls, gloves, overboots, a hood, and a gas mask.

The sensation of wearing all that gear and being escorted into a tear gas-filled "gas chamber" is something some trainees have to endure. No raw recruit is quite prepared for inhaling tear gas. Thus, any face mask with a poor seal or protective equipment that is worn poorly will be visible in this scenario.

In other training scenarios, you are compelled to take off your mask and give your complete name before being permitted to run outdoors to escape the effects of the tear gas.

The MOPP Gear

MOPP ensemble is another name for MOPP gear. The apparatus consists of an overgarment, overboots, gloves, a gas mask, and a hood to protect the wearer from nuclear, chemical, or bacterial agents.

In the past, layers of activated charcoal were used to manufacture MOPP overgarments to offer the garment's protective function. The outdated activated charcoal suits, which leave a noticeable black and powdery residue after use, have given way to more lightweight carbon beads and more practical clothing designs.

The gas mask has replaceable air filters that need to be changed regularly, and the whole thing needs to be decontaminated after use in the field. There are specialized field-operational decon methods for individuals who must wear MOPP gear during a drill or event.

When to wear MOPP Gear?

A variety of situations call for the use of MOPP gear and the measurement of MOPP levels. Most modern service members will encounter this during their basic training, their first duty assignment, and even while they are on deployment.

Although U.S. troops haven't been directly targeted by nuclear, chemical, or biological weapons in most American wars in the twenty-first century, this doesn't indicate that these weapons haven't been employed.

The civil war in Syria is an outstanding illustration of this. In 2019, National Public Radio (NPR) reminded us that during the civil war, "Syrian President Bashar Assad's regime carried out 98 percent" of all chemical assaults, "...dropping chlorine gas, sarin and sulfur mustard gas on Syrian civilians."

As seen above, chemical warfare is still a top concern when defending soldiers on the battlefield.

It's never a good idea to presume that the enemy will follow the Geneva Conventions, international law, etc. when combatting terrorists, rogue states, or other situations. The Geneva Protocol forbids "asphyxiating, poisonous or other gases, and of all analogous liquids, materials or devices" and "bacteriological methods of warfare."

However, it is never safe to assume that such warfare won't occur on the battlefield or as part of a terror campaign only because it constitutes a war crime.

MOPP Limitations

  • Heat Exhaustion - People wearing protective gear who work hard may become heat exhausted anytime, but it is most common during hot weather. 
  • Work Rate - The total quantity of work a person can perform will be impacted by respiratory resistance, a rise in body temperature, and psychological and physical stress. 
  • Five Senses- The senses and linked abilities, including motor skills, the ability to see clearly, and vocal communication, will function less effectively. 
  • Personal Needs- People cannot maintain complete chemical protection for extended periods while caring for their personal needs, such as wound care, personal hygiene, sleep, and waste removal. 
  • Eating- It is impossible to eat while wearing a gas mask. Depending on the type and level of contamination, troops may be able to eat in an NBC environment. 

The Five MOPP Protection Levels

The MOPP levels are assigned reminiscent of the post-9/11 threat situation levels used in the initial months after the 9/11 attacks. 

The MOPP level ranges from 0 to 4. Soldiers must constantly be ready since they are based on current chemical and biological threats and can escalate in minutes. 

Standardized MOPP levels make it simple for commanders to boost or lower security. Commanders don't need to give detailed explanations when ordering greater or lowered protection because the levels are uniform, and all soldiers know them. 

The MOPP gear components that take the longest to put on and have the least negative impact on mission performance are put on by soldiers first. The MOPP gear components that can be swiftly placed on and have the biggest negative impact on mission performance are put on last. 

This adaptability gives soldiers an advantage while donning their MOPP gear.

The rest of the equipment needed to protect the troops includes overgarments, gas masks and hoods, boot covers, and gloves.


  • Carry a protective mask, and ensure that individual protective gear is within arm's reach.

What Is The Army MOPP Gear And What Does MOPP Level 4 Mean

When operating in a situation where an opponent can launch an NBC attack, or even just the capacity to do so, MOPP Zero is not a sign that "no threat at all" exists. Instead, it refers to the minimal level of awareness that is necessary.

In addition to having the MOPP equipment close at hand (in the work area, vehicle, combat position, or a similar location), soldiers carry a protective mask with LCE. 

When the enemy can use NBCs, but chemical warfare has not started, or when forces are first sent outside the theater of operations, MOPP zero is appropriate. 

While not having to wear an overgarment or mask, soldiers can still have access to them when needed, thanks to MOPP zero. 

Until needed, the battle dress overgarment should be tightly closed in the vapor-barrier bag. The soldiers carry the M258A1 decontamination kit, M8/M9 detector paper, and NAAK.


  • Suit worn. Mask, gloves, and boots carried.

What Is The Army MOPP Gear And What Does MOPP Level 4 Mean

With this threat, soldiers wear only the protective overgarment; the remainder of the outfit should be carried or maintained nearby for quick access. 

It can be worn directly over their underwear in hot weather, and the jacket can be left open for air, but the pants must be kept closed. They put on the protective helmet cover and fastened the M9 paper to the overgarment. 

The reaction time needed for soldiers in MOPP1 to adopt MOPP4 protection against an attack is cut in half, from 8 minutes to 4.

This level of risk denotes that while there is no immediate threat to the troops, an attack could occur at any time or when contamination is nearby.


  • A suit and boots are worn. Gloves and mask carried.

What Is The Army MOPP Gear And What Does MOPP Level 4 Mean

MOPP 2 is essentially worn under "yellow alert" circumstances—"alarm yellow" is a typical identifier—where the overgarment and overboots are worn—a protective posture that presumptively anticipates the necessity for the remaining protective gear to be necessary without notice. 

Once troops are in MOPP2, they can quickly transition to higher MOPP levels by putting on the overboots, which take around three to four minutes. Soldiers can leave their overgarment jackets open in hot weather for ventilation, but they must maintain safety. 

Although MOPP 2 doesn't always mean that an assault is about to happen, individuals wearing it will find it much simpler to put on and wear the remainder of their equipment should the situation worsen.


  • Suit, boots, and mask worn. Gloves carried.

What Is The Army MOPP Gear And What Does MOPP Level 4 Mean

In MOPP3, soldiers don protective masks and hoods—except the gloves— nearly completing the level of protection. This level may have a vapor hazard, contact contamination, or other risks. 

However, this causes severe work-related interference. The mask and hood limit vision, heat stress increases, and there is a higher danger of heat exhaustion. Soldiers in hot weather may pull up the protective mask hood and open the overgarment jacket for ventilation, but they must keep their trousers fastened.


  • All protection is worn.

What Is The Army MOPP Gear And What Does MOPP Level 4 Mean

Lastly, MOPP level 4 is by far the most terrifying. 

The entire MOPP ensemble must be worn in this protective posture, including overgarments, overboots, masks, hoods, and gloves.

Personnel close their overgarments, tighten all drawstrings to prevent gaps, wear protective gloves, and enclose themselves. When the maximum level of protection is required or when CB agents are present but the actual danger cannot be identified, MOPP4 is employed.

Soldiers wear NBC rubber gloves with cotton liners to protect their hands. They finish the protection by pulling the hood down, adjusting it, and closing the overgarment. 

Like previous MOPP levels, flexibility is incorporated into the system's design to relieve the individual. The overgarment may be left open once the danger has been identified and preventative measures have been used.

MOPP4 has the most detrimental influence on a person's efficacy and efficiency.

Mask-Only Posture

If they are shielded from direct skin contact with liquid or solid contamination (transfer hazards), soldiers do not have to wear protective overgarments or rubber gloves when working in a polluted area. 

Examples of this type of partial shielding against contamination include tanks, some vans, and some structures. Soldiers may be exposed to vapor dangers but not transfer hazards inside these shelters. 

For instance, a teletype operator in a sealed communications van can work safely and much more effectively while wearing a mask.

What Is The Army MOPP Gear And What Does MOPP Level 4 Mean

  1. The value of a mask-only posture's enhanced efficiency must be weighed against its increased risk. Soldiers within may be exposed to a transfer hazard if weapons, fire, or accident breach the shelter. When a shelter is breached, regular clothing offers temporary transfer risk protection.
  2. Before leaving their bunker, soldiers in mask-only posture must assume the proper MOPP level. Returning soldiers must carefully avoid introducing liquid contamination inside the shelter to preserve mask-only posture. The mask-only command is appropriate in the following circumstances:
  • There haven't been any chemical attacks, and the troops outside are at MOPP3 or MOPP4.
  • The unit is in a downwind vapor-hazard area with troops outside MOPP4.
  • There has been an attack, and nonpersistent vapor is the only danger.

The choice to switch to mask-only for soldiers shielded from liquid-agent contact ultimately rests with the commander. The command "mask only" is inappropriate when blister-agent dangers are present.

System Flexibility

The MOPP system is versatile and adaptable. The secret to offering the best protection with the least amount of risk while still enabling mission completion is flexibility. 

Flexible MOPP protection enables subordinate commanders to change the amount needed for combat success in specific circumstances. 

Additionally, commanders can assign all or a portion of their units to multiple MOPP levels or approve changes within a single level.

What Is The Army MOPP Gear And What Does MOPP Level 4 Mean

a. Taking ownership of MOPP Levels. 

Minimum MOPP levels must be directed by corps, and higher-level commanders must also recommend greater MOPP levels proportional to the threat. 

They are informed about any strategic or tactical intelligence pointing to the potential employment of NBC weapons. The primary duty for improving the defensive posture of the unit falls to these commanders. 

Division and subordinate commanders are responsible for issuing orders for MOPP2 through MOPP4. 

However, the company commander, platoon leader, or squad leader has the final say. What the unit can and cannot do at this level is clearer.

Based on situational analysis and instructions from higher command, the leader decides whether to tighten or loosen the unit's defensive posture. 

This level of final accountability keeps the system's flexibility. The leader below the established minimum level cannot lower the defensive posture level.

b. changes to the MOPP levels. 

Each MOPP level has a lot of flexibility, allowing for changes depending on the circumstance. Certain modifications to MOPP gear wear prevent unit efficiency decline. 

Commanders must consider these variances about the potential for contamination and mission success. To alter MOPP, commanders should make these choices immediately. The following lists some recommended changes.

  1.  At MOPP1, MOPP2, or MOPP3, soldiers may leave their overgarment jackets open to improve ventilation. At MOPP3, they may also leave their hoods up or down. The threat, temperature, and unit work rate affect the commander's decision to deploy this variant.
  2. The overgarment can be worn directly over underwear or the battle dress uniform (BDU). The temperature and the staff's productivity are deciding variables.
  3. Soldiers must wear safety gloves when handling decontaminated equipment at MOPP1 through MOPP3. By doing this, contact with substances that might adhere to the equipment's surface is avoided.
  4. The commander may change the MOPP levels when the mission is critically important and residual nuclear effects pose the only threat. The commander's primary concern is gamma radiation, which MOPP gear cannot shield against, as was previously mentioned. The commander may opt to change the unit's posture if it is found that there is only a low-level residual radioactive threat due to mission requirements. By doing this, heat stress-related performance deterioration of the unit is decreased.
  5. Risks include beta particle burns and alpha particle ingestion. As showers are no longer a part of the decontamination process, another issue is the bigger one of eliminating radioactive particles from the hairy parts of the body. Soldiers may, as a last resort, use the M258A1 kit's wet wipes for this usage. Although neither circumstance significantly reduces the unit's performance, both must be considered.
  6. One way to change the protective posture is to have the soldiers use the cloth liners that come with their butyl gloves. By doing this, as much exposed skin as possible is covered. Instead of using protective masks, soldiers might cover their mouths with handkerchiefs or other dust-proof materials. The primary considerations are reducing skin contact with radioactive contamination and avoiding intake of radioactive particles. Soldiers will lessen the risk of beta burns and alpha particle ingestion. They will not need additional decontamination procedures if they can complete the operation while wearing their full MOPP gear.

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