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Back to Archives | Back to July 2010 Contents 

Understanding Performance Standards for Law Enforcement CBRN Protective Apparel

By Robert J. Eckroade, Market Specialist, CBRN Products, W. L. Gore & Associates Incorporated, Newark, Delaware

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n September 11, 2001, the nature of threats to public safety changed. The country came to realize that there was a much greater probability that weapons of mass destruction (WMD) could and would be used in an attack. This in turn created a new reality of personal protection for the law enforcement community, which became more difficult and complex. State, local, and regional law enforcement teams now are expected to play principal roles in the domestic war against terrorism and potential terrorism response missions.

Preparation for the eventuality of an attack must include planning, training, detection equipment, and personal protective equipment, which allow law enforcement personnel to effectively respond to hostilities and perform law enforcement functions in and around contaminated environments. Law enforcement officers must be protected from a range of hazardous agents, yet protective suits must minimize interference with the officers’ ability to respond.

These new responsibilities place increasing demands on the personal protective apparel officers will rely upon during chemical, biological, radiological, and nuclear (CBRN) incidents. To assist in the critical task of evaluating and selecting personal protective equipment (PPE), several organizations have sought to provide additional resources, PPE performance standards, and new generations of protective products and technology needed by the law enforcement community. This group includes the federal government, standards organizations such as the National Institute of Justice (NIJ) and the National Fire Protection Association (NFPA), equipment manufacturers, and other knowledgeable groups.

Protection Strategies and Approaches

An important part of law enforcement terrorism response readiness is having appropriate PPE. Law enforcement, while having myriad choices, has essentially been limited to borrowing technology from either military or hazardous materials applications. The borrowed technologies have often come from Department of Defense programs, given the military’s long-standing preparedness for potential use of chemical warfare agents by enemy forces. Additionally, although far from ideal, some law enforcement teams have adopted products originally developed for hazardous materials response teams that routinely deal with toxic chemical spills and related hazards. So, although PPE exists for military and hazmat applications, it has become clear that these products do not meet the unique operational and protection requirements required by law enforcement to perform under hostile conditions.

CBRN Threats

With acronyms such as WMD and CBRN becoming more pervasive in public safety, law enforcement personnel are seeing their missions expanded to deal with potential terrorism, involving dangerous, new agents. The magnitude of potential events requires that all first responders be prepared for the unique hazards associated with WMD-based terrorism incidents. These threats involve a spectrum of different substances and scenarios, including chemical, biological, and radioactive agents, which must be anticipated.

Chemical threats include the use of chemical warfare agents (CWA) and toxic industrial chemicals (TIC) against civilian populations. Chemical warfare agents are specifically designed to harm humans through either respiratory or skin exposure. As an example, the CWA sarin has already been used in one attack in Japan, causing multiple deaths of both civilians and first responders, who did not realize initially what the attacking agent was.1 Toxic industrial chemicals, although not as toxic as chemical warfare agents, are much more pervasive, exist in larger quantities, and are more readily accessible. For these reasons, many law enforcement teams often classify toxic agents as more dangerous than chemical warfare agents. TICs were used by terrorists in Iraq, who combined explosives with chlorine containers, resulting in a number of civilian casualties during 2007 and 2008.2 Also, though not acts of terrorism, law enforcement officials must routinely deal with serious health threats from “cocktails” of multiple hazardous chemicals encountered during raids on clandestine drug laboratories.

Biological agents including pathogens and toxins also pose serious threats during law enforcement response to terrorism. The dissemination of anthrax spores through the U.S. Postal Service in fall 2001 shows how pervasive such an attack can be.3 The majority of biological hazards are airborne, where disease is spread through the respiration of biological agents; however, some biological hazards can be manifested through skin contact, or more aptly, blood contact with non-intact skin. While not terrorism, bloodborne pathogens such as HIV and Hepatitis are also threats to which law enforcement personnel may be exposed.

Ionizing radiation emanating from radioactive material is perhaps the most difficult hazard to approach. Certainly, the threat for high levels of radiation coupled with intense energy associated with a nuclear weapon detonation obviates any hope for short-term, short-range protection. Nevertheless, the law enforcement community also is concerned about other radiological hazards, such as those that may occur through the use of a radioactive dispersal device (RDD or a “dirty bomb”) in which conventional explosives are coupled with commercial radioactive material (such as that used in health-care imaging equipment) to spread ionizing radiation over large areas. The mantra of protection from radiological hazards is shielding, distance, and time. All clothing will protect against alpha particles—with some forms of protective clothing effective against low-energy beta radiation. However, protection from high-energy beta particles, gamma rays, and X-rays generally exceeds the capabilities of all conventional protective clothing.

Protection Principles

The effectiveness of personal protective equipment in keeping law enforcement personnel safe from CBRN hazards involves a combination of appropriate materials and overall clothing design. Materials must be selected to act as barriers against the specific agents of concern; this is ensured through material-level testing. Additionally, the overall ensemble design, including closures and interfaces, must limit ingress of hazardous agents to safe levels; this is measured by system-level tests.

Material-level testing for CBRN hazards includes chemical permeation resistance and chemical penetration resistance. Chemical permeation resistance involves limiting the amount of chemical that passes through on a molecular level. Tests have been developed to determine how well the material keeps individual chemicals from permeating at levels that can be dangerous to the wearer. It is important that materials be evaluated against a representative battery of chemicals for a range of properties and hazards that may be encountered. For example, air-permeable, carbon-based materials may reduce chemical warfare agent permeation to an acceptable exposure level versus a military requirement; however, several toxic industrial chemicals easily permeate these materials at relatively high rates. For CBRN protection, the commonly accepted approach based on military protocol is to measure the total amount of chemical permeating a given area of material over a specified period of time. The measured amount of permeating chemical is compared to toxicological end points that have been established by military and civil subject matter experts. These toxicological end points are reflected in both Department of Defense specifications and in the civil third-party standards, which will be discussed later in this article.

Chemical penetration resistance refers to bulk liquid transfer (as opposed to molecular transfer) through a material. Materials should be tested for penetration resistance against a battery of potential toxic industrial chemicals. For example, many responders are surprised to find that some of the “borrowed technology” PPE they use does not protect against penetration of common acids such as sulfuric acid and hydrochloric acid. Just as materials are tested for their barrier properties against chemicals, materials also can be tested for biopenetration resistance. Biological agents can pass through materials as extremely tiny particles in minute amounts of liquid too small to see.

Lastly for material-level testing, it is also important to characterize materials in terms of their strength and durability. There are many barrier materials provided by industry, but clothing based on these materials, in some cases, may be easily compromised through contact with physical hazards or wear and tear. The physical properties for materials in terms of their overall resistance to physical hazards such as tears, punctures, abrasion, and repeated flexing is a critical factor in choosing the correct protective clothing material.

The importance of system-level tests of CBRN PPE cannot be overlooked. Even when constructed of an excellent barrier material, CBRN PPE will essentially offer little to no protection if chemical or biological agents can penetrate openings in the garment, bypassing the barrier material altogether. Any opening of the clothing, such as the front closure, must be designed to minimize leakage of outside contamination into the clothing. This challenge becomes even tougher when the clothing design must consider all interfaces between the garment and other ensemble elements. CBRN PPE garments have to interface with respirators, gloves, and footwear, at a minimum, and each point of attachment should offer similar protection as the base materials used in the construction of the garment. Thus, the overall integrity of the garment design and construction becomes equally important to the performance of the barrier material.

There are two principal tests for measuring garment and ensemble integrity. One comprehensive evaluation is Man-in-Simulant-Test (MIST). This technique, employed by the military for years as a way of testing garments against battlefield chemical warfare agents, is now being applied to first-responder CBRN protective clothing and ensembles. MIST involves measuring how much surrogate vapor passes through the garment onto special adsorbent pads located all over the test subjects’ bodies while the test subjects perform a series of exercises which replicate response activity. Laboratory analysis of the adsorbent pads yields how much surrogate chemical penetrated the ensemble and allows for the calculation of protection factors—ratios of outside-the-suit to inside-the-suit concentrations. Additional calculations provide protection factors for individual body locations and the overall ensemble; these can be compared against established minimum requirements in the relevant standard.

Protective clothing is also evaluated using an overall liquid integrity test, commonly called the “shower test.” In this test, PPE ensembles are subjected to a liquid spray exposure to assess the overall liquid protection provided. Responders are interested in this evaluation as it closely simulates liquid challenges an ensemble will experience going through a wet decontamination procedure. Typically, no sign of liquid ingress is the acceptance criteria. Liquid integrity testing is also useful in specifically assessing the performance of garment closure systems, seam quality, and overall design integrity.

Available and Emerging Standards

Standards play an important role in defining minimum requirements for protective clothing in terms of protection and operational performance. In this fashion, standards encompass a range of requirements that would otherwise be difficult for individual departments to specify. Additionally, standards provide a level basis of comparison, helping departments to evaluate different PPE options against a common benchmark.

A standard that already exists and is being used by law enforcement today is NFPA 1994, Standard on First Responder Protective Ensembles for CBRN Terrorism Incidents. This standard for protective ensembles couples clothing systems with CBRN-approved respiratory protection to provide multiple classes of ensembles that address varying threat scenarios. The most recent edition, from 2007, addresses threat scenarios through three different classes of protective ensembles.

  • Class 2 sets the highest level for protection against CBRN threats in the standard. Ensembles and their barrier materials in Class 2 must meet the most stringent permeation requirements and the highest MIST system-level requirements. Requirements for Class 2 are aligned with the use of self-contained breathing apparatus (SCBA) and should be employed whenever the threat is known and conditions are judged as immediately dangerous to life and health (IDLH). Many responders commonly refer to this threat scenario as “the hot zone.”

  • Class 3 ensembles provide lower levels of protection against CBRN threats. Ensembles and their barriers in Class 3 have permeation requirements and system-level requirements that align with the use of CBRN air-purifying respirators (APR) or powered air-purifying respirators (PAPR). These scenarios reflect conditions below IDLH and are often referred to as “the warm zone.” Since warm zone operations are often longer in duration, Class 3 ensembles are required to have a barrier material that passes a minimum 200 Watts per square meter Kelvin Total Heat Loss (THL) requirement. This THL requirement is typically achieved through the use of breathable barrier materials.

  • Class 4 ensembles are for protection against biological and radiological particulates only, such as for “white powder” calls. These ensembles do not provide chemical agent protection or toxic industrial chemical protection. Class 4 garment barrier materials have higher THL requirements than Class 3 ensembles.

The NFPA 1994 standard is recognized by the Responder Knowledge Base (, which lists compliant products already being purchased by law enforcement for each the of specified ensemble classes.

Additional standards for law enforcement are currently being developed to help ensure law enforcement needs are fully addressed. The National Institute for Justice (NIJ) expects to soon publish a law enforcement protective ensemble CBRN standard. The proposed NIJ standard, available to the public in draft form at the time of this writing, establishes four law enforcement response levels (LERL). These proposed levels incorporate many of the protection requirements established with NFPA 1994 and related standards. However, there are two major, overarching differences across all NIJ LERLs and NFPA 1994 levels.

  1. NIJ requires more extensive preconditioning of barrier materials prior to permeation testing, and

  2. NIJ requires several additional human factors and ergonomics tests beyond what is required in the relevant NFPA standard.

An additional difference between the standards is that NIJ has a minimum THL requirement in an above IDLH ensemble (LERL-2) not found in NFPA 1994.

The following is a brief summary of each of the four levels as they exist in the August 2008 draft of NIJ Standard - 0116.00: CBRN Protective Ensemble Standard for Law Enforcement, and how they compare to their NFPA counterpart.

LERL-1. The highest level of protection in the NIJ standard is the LERL-1, which requires a self-encapsulating suit for conditions unknown or known to be above IDLH environments, comparable to NFPA 1991, Standard on Vapor–Protective Ensembles for Hazardous Materials Emergencies. The NIJ and NFPA standards both require material permeation testing to 24 TICs and 2 CWAs and have flash-fire requirements. Also, as with NFPA 1991, ensembles compliant to LERL-1 will require the use of an SCBA. One key difference between the standards is that LERL-1 utilizes MIST for the system-level test, whereas NFPA 1991 utilizes the sulfur hexafluoride (SF6) test. Note that users often refer to self-encapsulating PPE as “level A” suits.

LERL-2. The LERL-2 corresponds to NFPA 1994, Class 2, with very similar barrier material chemical permeation and MIST system-level requirements. LERL-2 is for use in conditions unknown or known to be above IDLH environments and requires the use of an SCBA. One key difference between the standards is that NIJ proposes adding a minimum 450 Watts per square meter Kelvin THL requirement for this level, which is not included in NFPA 1994, Class 2.

LERL-3 The LERL-3 corresponds to NFPA 1994, Class 3. The requirements are closely aligned between the NIJ and the NFPA standards for chemical permeation challenges and MIST system-level testing. Both standards require the use of an APR or PAPR for environments known to be below IDLH. Additionally, there are THL requirements for both NFPA 1994, Class 3, and the NIJ standard, although NIJ is proposing higher levels than NFPA (450 Watts per square meter Kelvin versus 200 Watts per square meter Kelvin).

LERL-4. The LERL-4 is most similar to NFPA 1994, Class 3, for materials, system-level performance, and use of an APR or PAPR. Primary differences with LERL-4 concern reduced durability needs versus what is required by LERL-3.

Recommended Selection Practices

Evaluation and selection of protective ensembles require an understanding of both the CBRN hazards personnel may face during terrorism response missions and the capabilities needed to respond to hostilities and perform law enforcement functions in a potentially contaminated environment.

The use of performance standards in the selection of CBRN protective clothing should be a prerequisite. These standards arise from balanced groups that have worked together to determine minimum requirements for end user protection and operational performance. The level of investment and expertise needed to develop these recommendations is typically beyond the resources of individual departments. Standards also provide a basis for departments to evaluate different PPE options against a common reference point.

Fortunately, manufacturers have responded to better meet law enforcement needs for enhanced response capabilities. A range of CBRN PPE compliant to independent third-party performance standards is now commercially available from multiple manufacturers; it’s no longer necessary for law enforcement to compromise by choosing borrowed technologies.

Departments can help ensure officer safety by specifying only CBRN ensembles that are compliant with third-party standards. Within the applicable standard, departments must identify the class or level relevant to the officer’s operational needs or anticipated mission requirements. Further, departments should seek third-party documentation for any additional PPE performance they wish to specify. An individual department’s performance requirements, above what is required in a standard, can include testing of additional CWAs, TICs, higher THL or mechanical strength, and flame resistance.

Since 9/11, it has become clear that new threats to public safety exist and that law enforcement teams now play an increasing role in the domestic war on terrorism. Fortunately, departments no longer must accept compromises associated with borrowed PPE technologies when planning for CBRN terrorism response missions. Recognized performance standards already exist and additional standards are in development. These standards can assist and guide law enforcement in the critical task of evaluating and selecting CBRN PPE for a range of potential response missions, to enhance both officer safety and terrorism response capabilities. ■


1Kyle B. Olson, “Aum Shinrikyo: Once and Future Threat?” Emerging Infectious Diseases 5, no. 4 (1999): 513–516, (accessed May 24, 2010).
2Anthony H. Cordesman and Emma R. Davies, Iraq’s Insurgency and the Road to Civil Conflict (Westport, Conn.: Praeger Security International, 2008), 580.
3Frank Gottron, The U.S. Postal Service Response to the Threat of Bioterrorism through the Mail, February 11, 2002, RL31280, CRS-4, (accessed May 24, 2010).

Please cite as:

Robert J. Eckroade, "Understanding Performance Standards for Law Enforcement CBRN Protective Apparel," The Police Chief 77 (July 2010): 16–19, (insert access date).



From The Police Chief, vol. LXXVII, no. 7, July 2010. Copyright held by the International Association of Chiefs of Police, 515 North Washington Street, Alexandria, VA 22314 USA.

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