chemicalppe

Chemical Protective Clothing (CPC)

The purpose of chemical protective clothing and equipment is to shield or isolate individuals from the chemical, physical, and biological hazards that may be encountered during hazardous materials operations. During chemical operations, it is not always apparent when exposure occurs. Many chemicals pose invisible hazards and offer no warning properties.

These guidelines describe the various types of clothing that are appropriate for use in various chemical operations, and provides recommendations in their selection and use. The final paragraph discusses heat stress and other key physiological factors that must be considered in connection with protective clothing use.

It is important that protective clothing users realize that no single combination of protective equipment and clothing is capable of protecting you against all hazards. Thus protective clothing should be used in conjunction with other protective methods. For example, engineering or administrative controls to limit chemical contact with personnel should always be considered as an alternative measure for preventing chemical exposure. The use of protective clothing can itself create significant wearer hazards, such as heat stress, physical and psychological stress, in addition to impaired vision, mobility, and communication. In general, the greater the level of chemical protective clothing, the greater the associated risks. For any given situation, equipment and clothing should be selected that provide an adequate level of protection. Overprotection as well as under-protection can be hazardous and should be avoided.

Protective Clothing Applications.

Protective clothing must be worn whenever the wearer faces potential hazards arising from chemical exposure. Some examples include:

Emergency response;

Chemical manufacturing and process industries;

Hazardous waste site cleanup and disposal;

Asbestos removal and other particulate operations; and

Agricultural application of pesticides.

Within each application, there are several operations which require chemical protective clothing. For example, in emergency response, the following activities dictate chemical protective clothing use:

Site Survey: The initial investigation of a hazardous materials incident; these situations are usually characterized by a large degree of uncertainty and mandate the highest levels of protection.

Rescue: Entering a hazardous materials area for the purpose of removing an exposure victim; special considerations must be given to how the selected protective clothing may affect the ability of the wearer to carry out rescue and to the contamination of the victim.

Spill Mitigation: Entering a hazardous materials area to prevent a potential spill or to reduce the hazards from an existing spill (i.e., applying a chlorine kit on railroad tank car). Protective clothing must accommodate the required tasks without sacrificing adequate protection.

Emergency Monitoring: Outfitting personnel in protective clothing for the primary purpose of observing a hazardous materials incident without entry into the spill site. This may be applied to monitoring contract activity for spill cleanup.

Decontamination: Applying decontamination procedures to personnel or equipment leaving the site; in general a lower level of protective clothing is used by personnel involved in decontamination.

Ensemble Selection Factors:

Chemical Hazards. Chemicals present a variety of hazards such as toxicity, corrosiveness, flammability, reactivity, and oxygen deficiency. Depending on the chemicals present, any combination of hazards may exist.

Physical Environment. Chemical exposure can happen anywhere: in industrial settings, on the highways, or in residential areas. It may occur either indoors or outdoors; the environment may be extremely hot, cold, or moderate; the exposure site may be relatively uncluttered or rugged, presenting a number of physical hazards; chemical handling activities may involve entering confined spaces, heavy lifting, climbing a ladder, or crawling on the ground. The choice of ensemble components must account for these conditions.

Duration of Exposure. The protective qualities of ensemble components may be limited to certain exposure levels (e.g. material chemical resistance, air supply). The decision for ensemble use time must be made assuming the worst case exposure so that safety margins can be applied to increase the protection available to the worker.

Protective Clothing or Equipment Available. Hopefully, an array of different clothing or equipment is available to workers to meet all intended applications. Reliance on one particular clothing or equipment item may severely limit a facility's ability to handle a broad range of chemical exposures. In its acquisition of equipment and clothing, the safety department or other responsible authority should attempt to provide a high degree of flexibility while choosing protective clothing and equipment that is easily integrated and provides protection against each conceivable hazard.

Material Chemical Resistance:

Permeation: The process where a chemical dissolves in and /or moves through a protective clothing material on a molecular level.

Degradation: The loss of or change in the fabric's chemical resistance or physical properties because of chemicals, its use or surrounding conditions (e.g. sunlight)

Penetration: The movement of chemicals through stitched seams, pinholes and zippers or imperfections in a protective clothing material.

Rate of Permeation: The rate at which a chemical dissolves in and/or moves through a protective clothing material.

Breakthrough Time: The time from an initial exposure until hazardous material is detectable on the inside of the Chemical Protective Clothing (CPC).

Rate of permeation and the breakthrough time may vary depending on the following conditions:

Clothing material type and thickness

Manufacturing method

The concentration(s) of the hazardous substance

Temperature

Pressure

Humidity

The solubility of the chemical in the clothing material

The diffusion coefficient of the permeating chemical in the clothing material

Chemical Permeation Index Numbers:

The chemical permeation index numbers provide a useful guide to help in selection of the best protective materials when there is more than one choice available or to provide some relative risk assessment if data is available for only one type of material. Final selection should also include degradation data when it is available.
Index 0 and Index 1 apply to the most resistant materials towards a specific chemical or test mixture.

Index Number 0 indicates a highly resistant material for this chemical and is one of the best of the models tested against this chemical.

Index Number1 indicates a highly resistant material for this chemical and may often be accepted by an industrial hygienist for harmful chemicals (e.g., as toxic as toluene or as corrosive as concentrated sodium hydroxide or as irritating as acetaldehyde).

Index Number 2 requires a greater degree of judgment by an industrial hygienist before it will be accepted. Industrial hygienists will not feel comfortable in recommending Index 2 materials for chemicals that are harmful (where a relatively small dose has a medium to moderate toxicity).

Index Number 3 materials are not usually sufficiently protective to be recommended by industrial hygienists unless there is no other choice or unless the work involves protection only against occasional splashes or compounds that are not very harmful.

Index Number 4 materials are usually not acceptable for protection in any situation except occasional splashes. When splashes occur with materials in either Index 3 or 4 the gloves, or other types of protective clothing, should be immediately removed and exchanged for new ones.

Index Number 5 materials may be considered dangerous by most industrial hygienists because of the lack of protection they offer towards the chemical(s) tested.

Chemical protective clothing (CPC) test results with classification Index Numbers of 4 or 5 may exhibit one or more forms of degradation. It is important to note that a manufacturer's material and model which has an index number of 4 or 5 against one particular chemical may in fact be rated with an Index Number of 0 or 1 against some other chemical. Therefore, these Index Numbers are not to be construed as a general rating of a CPC. The rating is only applicable for protection against the specific chemical referenced and under the conditions of the measurements used, which include a specific manufacturer's material and model number.

Mixture of chemicals can be more aggressive towards CPC materials than a single chemical. Even small amounts of a chemical that permeates quickly may provide a path that speeds up the permeation of other chemicals. The National Institute of Occupational safety and Health (NIOSH) is currently conducting research on the CPC materials.

See the following links for more information on Chemical Protective Clothing, Permeation numbers and degradation.

Chemical, Toxicity, Safety and Environmental Analysis Information for Acetaldehyde and Chemical Protective Clothing

Selection of Chemical Protective Clothing:

Selection of CPC is a complex task. It should be done by workers with training and experience. Under all conditions, clothing should be selected by comparing the clothing with the hazard. Also the clothing should be inspected before being purchased and its use and performance should be discussed. It is the employer's responsibility to make sure that the PPE is adequate and safe for the work to be performed.

The selection of CPC depends on the type and physical state of the chemicals. This information is determined during site characterization. Site characterization gives the information needed to identify site hazards and to select ways to protect the workers. It is conducted in three stages:

Before site entry

On-site survey

Continuous monitoring

PPE or CPC are selected based upon the data collected in all three stages of site characterization. Once the chemicals have been identified, sources should be consulted to identify CPC that is resistant to permeability and degradation.

It is important to note that no material protects against all chemicals. The concentration and form of the contaminant is critical in determining the proper CPC. Some materials may protect against a chemical in a low concentration for quite a long time. This may mean that some CPC's work life may decrease with higher concentrations.

Heat Transfer Characteristics:

An important factor in the selection of CPC is the transfer of heat. Since most CPC does not allow air and moisture to flow freely, then cooling by evaporation is limited. The thermal insulation value of CPC is a measure of the clothing's ability to reduce heat loss by some way other than evaporation. The larger the thermal insulation value, the greater the insulating of the garment and so, the lower the heat transfer rate. Clothing with the lowest thermal insulation value should be selected in hot environments or for high work rates.

Other Considerations:

Durability : (Does the material have sufficient strength to withstand the physical stress of the task ? Will the material resist tears, punctures and abrasions ? Will the material take repeated use after contamination or decontamination?)

Flexibility: Will the CPC interfere with the workers' ability to perform their assigned tasks? (Especially important for the use of gloves)

Temperature Effects: Will the material maintain its protective and flexible characteristics under hot and cold extremes?

Compatibility with Other Equipment: Does the clothing restrict the use of another necessary piece of protective equipment? (Especially important for suits that restrict hardhat use in a hardhat area)

Ease of decontamination: Will the material pose any decontamination problem? Should disposable clothing be used?

Duration of Use: Can the required task be done before chemical breakthrough occurs or degradation becomes serious?

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Last Update: March 31, 2000

Prepared by : Serdar Z. Elgun