Decontamination for Hazardous Materials Incidents

By Shirley Ayers

As part of the effort to control hazardous materials or weapons of mass destruction, emergency action is sometimes required to make victims, personnel, their equipment and the environment as safe as possible by the removal or isolation of hazardous materials - a process called decontamination.

The entire process of decontamination is directed toward confinement of the contaminant within the Warm Zone and controlling it within the decontamination area. Removing contaminants from personnel and equipment is vital to lessening the potential of transferring contaminants outside of the hazard area. Proper decontamination is especially important in those instances where victims or injured personnel must be transported to medical facilities.

OSHA CFR 1910.120 - the Hazwoper regulation - requires organizations to develop, communicate and implement decontamination procedures before any employees or equipment may enter areas where the potential for exposure to hazardous substances exists. The decontamination procedures outlined and depicted in this program are in accord with the requirements of 1910.120 as well as with the National Fire Protection Association's standard 471, Responding to Hazardous Materials Incidents and NFPA 472, Standard for Professional Competence of Responders to Hazardous Materials Incidents. See Appendix A for a summary of these law and standards as they pertain to decontamination.

As is the case with any emergency response procedures, implementing decontamination successfully requires regular training and practice.

Contamination

In general, contaminants can be divided into seven different categories:
Highly acute toxicity contaminants cause damage to the human body as a result of a single or short-duration exposure. These substances can be found in solid, liquid, or gas forms and present risks to personnel from any route of exposure. Examples include potassium cyanide, acids, sodium hydroxide and nerve agents.
Moderate to high chronic toxicity contaminants include certain heavy metals, their derivatives, and potent carcinogens. They can be found in solid, liquid, or gas forms and present risks to personnel from any route of exposure. Examples include ethylene dibromide (EDB), organic mercury compounds and nitroamines.
Allergenic contaminants are substances that produce skin and respiratory hypersensitivity and present risks to personnel from both inhalation and direct skin contact. Personnel exposed to the same allergen at the same level of exposure may react differently. Examples of allergenic contaminants include diazomethane, formaldehyde, and isocyanates.
Flammable/combustible contaminants catch fire readily and burn in air. They may be found as a solid, liquid or gas. While flammable and combustible contaminants are hazardous due to their obvious fire hazard, they may also present contamination hazards. Examples include acetone, benzene, methanol, ethanol, and gasoline. Care should be exercised when determining PPE levels when dealing with flammables. Chemical resistant clothing is not fire resistive, and will not offer any protection against fire.
Highly reactive/explosive contaminants include peroxides, peroxide-forming compounds, and explosive materials. Some of these materials can react with the oxygen present in the atmosphere, while others are heat, shock, and friction sensitive. Among the materials that can form peroxides include ethers and some alkalines, such as vinyl compounds. The concentration of these contaminants plays an important role in determining the risk involved in decontamination. Specific examples of explosive contaminants include cyclohexane, diethyl ether, diisopropyl ether, and tetrahydrofuran.
Biological (etiological) contaminants are microorganisms such as viruses, fungi, and bacteria or their toxins that can cause illness, disease, or death. Bloodborne pathogens are included in this group. These contaminants can enter the body by ingestion, direct contact, or through the respiratory system. Examples include anthrax, botulism, smallpox, and hepatitis A, B, C, D and E.
Radioactive contaminants may be in the form of alpha or beta particles, or gamma wave radiation. Specific examples include cesium 137, cobalt 60, radon 222, uranium hexafluoride, and plutonium. If alpha-emitting contaminants are airborne as in dust or smoke they can become surface contamination on protective clothing or tools carried into the hazard area. These solid contaminants can enter the body through any routes of exposure, but usually by inhalation.

Direct vs. cross contamination

Contamination may be either direct or indirect. Direct contamination results from direct contact with the hazardous substance. Indirect, or cross contamination, results whenever a clean or uncontaminated element (person, animal, or object) comes into direct contact with a dirty or contaminated element. This is also called secondary contamination.

Direct contamination may occur during entry into the hazard area or by responders or equipment coming into direct contact with the contaminant in the decontamination area. Some common reasons for direct contamination include:

Poor site management practices;
Use of incompatible protective clothing;
Failure to identify potential safety problems;
Running out of breathing air in the Hot Zone;
Failure to decontaminate;
Fires in occupancies where hazardous materials may be stored or discarded;
Fires in clandestine drug labs.

Examples of how cross contamination may occur include:

A contaminated victim comes into physical contact with a clean person or other exposure such as ambulance;
A bystander or site worker crosses into the hazard area or comes into contact with a contaminated object within the hazard area;
A decontaminated responder re-enters the decon area or inner perimeter and comes into contact with a contaminated person or object.

The variety of ways contamination can occur makes it critical that hazard control zones be clearly marked and enforced. The more people directly or indirectly exposed to the contaminant, the bigger the decontamination problem will become.

Permeation

Contaminants can be located either on the surface of personal protective equipment (PPE) or they may have penetrated into the PPE material. Surface contaminants may be easy to detect and remove. Contaminants that have permeated a material may be difficult or impossible to detect and remove. If contaminants that have permeated a material are not or cannot be removed by decontamination, they may continue to permeate from the outside surface to the inner surface. This is called breakthrough, and can cause an unexpected exposure.

Five major factors affect the extent of permeation:

1. Physical state of chemicals
As a rule, gases, vapors and low-viscosity liquids tend to permeate more readily than high-viscosity liquids or solids.

2. Contact time
The longer a contaminant is in contact with a material, the greater the probability and extent of permeation. For this reason, minimizing contact time is one of the most important objectives of a decontamination program.

3. Concentration
As concentrations of the chemical or chemicals increase, the potential for permeation of personal protective clothing increases.

4. Temperature
An increase in temperature generally increases the permeation rate of contaminants.

5. Route of exposure
Contaminants that are inhaled or absorbed through the skin tend to pose a greater threat than contact.

SOPS

Although specific decontamination practices and methods will vary depending on the nature of the incident, the first step for agencies that may need to practice decontamination is to establish standard operating procedures (SOPs). SOPs establish basic guidelines for the Decon Unit Supervisor and Decon Team. SOPs should include methods to:

Avoid unnecessary contact with potentially hazardous substances. For example, responders should not walk through areas of obvious contamination, should avoid puddles, and should not directly touch unknown substances;
Use remote sampling and safe handling techniques;
Protect monitoring and sampling instruments by bagging. Openings in the bags can be cut to accommodate sampling ports and sensors to the atmosphere;
Use of protective clothing and equipment;
Use of disposable equipment where appropriate.

SOPs for setting up decon stations should adopt the basic principle that contaminated people and equipment generally flow from the dirty end - the area of highest contamination, to the clean end - the area of least contamination. Supplies and equipment should flow form the clean side to the dirty side. A multiple-step process is used to reduce contaminants to an acceptable level. This reduces the concentration of contaminants in any given area and results in a cleaner finished product. The decision as to how many stations will be established will be made based on the hazards involved and the complexity of the situation.

Decon Unit Supervisor

The Decon Unit Supervisor is the leader of the Decon Team, and has numerous duties and responsibilities. He confers with the hazardous materials officer, medical officer, chemists and other specialists to select the location of the decon area, decontamination method to be used, and proper protective clothing configuration for the Decon Team. After decon begins, he must evaluate the effectiveness of the selected method. He is responsible for briefing each entry team on the type of decon that will occur, and for making sure that each entry team undergoes decon whenever they leave the Hot Zone. The Decon Unit Supervisor is also responsible for documentation of the contaminants encountered, personnel passing through decontamination, protective clothing worn, length of exposure, and the decontamination procedure followed.

Decontamination Plan

According to OSHA, hazmat responders must develop and use procedures appropriate to their level of response and training.

Although decontamination is typically implemented after entry operations, decisions about the types of decon methods and procedures must be considered early in the incident as part of the hazard and risk evaluation process. Entry into the Hot Zone should not be permitted unless appropriate decontamination methods have been determined and established based on the hazards present, except in those situations where a rescue may be possible and emergency decon is available.

Every decontamination plan should include the following basic elements:

Location of the decon area;
The most appropriate decontamination methods based on the hazards present;
The number of decontamination stations that will be needed;
The layout of the decon area;
Methods to minimize responder contact with contaminants during removal of personal protective clothing and equipment;
Methods to control runoff and cross-contamination in the decon area;
The equipment and materials that will be necessary;
The number of personnel required to support the decontamination operation;
Proper personal protective equipment for decon team members;
Proper disposal methods for clothing and equipment.

The plan may need to be revised whenever the type of personal protective clothing or equipment changes, the response changes, or as new information about the hazards becomes available.

Decon Equipment

Following is the list of specific equipment needed to set up each decon station:

Plastic liners
Plastic drop cloths
Containment (20-30 gallons)
Decontamination solutions
Rinse water
2-3 long-handled, soft-bristled scrub brushes or sponges
bench or stools
air tanks or masks and cartridges depending on level
tape
boot covers
gloves
basins or buckets
soap and towels
water
water spray units
soap
field showers
changes of clothing

Night operations may require lighting, as visibility is often a problem. The path from the Hot Zone to the Decon areas should be well marked and lit to prevent entry team members from contaminating clean areas. Lighting should be provided from each decontamination station as well.

The Decontamination Process

The decontamination process should consist of a series of procedures performed in a logical sequence. For example, outer, more heavily contaminated items (i.e., outer boots and gloves) should be decontaminated and removed first, followed by decontamination and removal of inner, less contaminated items. Each procedure may be performed at a separate station in order to prevent cross contamination. The location of these stations is in the Warm Zone.

Entry and exit points should be conspicuously marked. Dressing stations for entry to the Warm Zone should be separate from redressing areas for exit from the Warm Zone. Personnel, who wish to enter clean areas of the decontamination areas such as locker rooms, must be completely decontaminated.

Decontamination of responders who initially come in contact with personnel and equipment leaving the Hot Zone will require more protection from contaminants than Decon Team members who are assigned to the last station in the decon line. In some cases, decontamination personnel should wear the same types of protective ensembles as responders into the Hot Zone. In other cases, decontamination personnel may be sufficiently protected by wearing liquid splash-protective suits when responders are required to wear vapor protective suit ensembles. The hazard and extent of contamination dictate the appropriate level of protection for the Decon Team.

Decontamination Methods

Decontamination methods involve either physically removing contaminants; inactivating contaminants by chemical neutralization or disinfecting, or removing contaminants by a combination of both physical and chemical means. Appropriate decontamination solutions will vary. Chemical protective clothing manufacturers and regulatory agencies generally do not provide specific recommendations for decontamination and there is no definitive list with specific methods recommended for specific chemicals and materials.

Specific decontamination procedures depend on a number of factors, but primarily on the specific types of contaminants involved. Highly toxic materials/contaminants generally require more detailed and thorough decontamination procedures than do less toxic materials. A thorough understanding of the hazardous materials involved as well as general principles and guidelines involved in decontamination is essential to implementing effective procedures.

Most often, decontamination is accomplished using detergents (surfactants) in water combined with a physical scrubbing action and rinsing. This process will remove most forms of surface contamination including dusts, many inorganic chemicals, and some organic chemicals. It may not be effective in removing oily or tacky organic substances such as PCB's in transformer oil. Furthermore, this form of decontamination is unlikely to remove any contamination that has permeated or penetrated the suit materials. Using organic solvents such as petroleum distillates may allow easier removal of heavy organic contamination but may result in other problems, including:

Permeation into clothing components, pulling contaminant with it;
Spread of localized contaminant into other areas of the clothing;
Generation of large volumes of contaminated solutions which require disposal;
Compromise of the integrity of seams and adhesives in PPE; and
Degradation of some protective clothing ensemble materials.

Contaminants are likely to collect in suit and body crevices, within closures or flaps, under fingernails, and in other places that may be missed or difficult to reach during decontamination. The decon process must pay particular attention to these areas, as well as to hands and feet.

Testing Decon Effectiveness

In order to re-use protective clothing or equipment, it is essential to demonstrate that adequate decontamination has taken place. This is not easily accomplished, since there are no completely accurate methods for non-destructively evaluating clothing or equipment contamination levels. Garment manufacturers should provide specific guidance. Methods that may assist in a determination include:

Visual examination of PPE for signs of discoloration, corrosive effects, or any degradation of external materials. Many contaminants, however, do not leave any visible evidence.
Wipe sampling of external surfaces for subsequent analysis. This may or may not be effective for determining levels of surface contamination, as the process depends heavily on the material-chemical contamination. Also, this method will not detect permeated contamination.
Analysis of the cleaning solution. This method is most effective if the original contaminant is known, which is usually not the case. It can show whether some of the chemical has been removed by the cleaning solution.
Use of air monitoring instrumentation.
Destructive testing. If a number of garments have been contaminated, it may be advisable to sacrifice one garment for destructive testing by a qualified laboratory with analysis of contamination levels on and inside the garment.

Due to the difficulty in assessing contamination levels in PPE before and after exposure, the Decon Unit Supervisor must determine whether the respective clothing or equipment can be re-used. Re-use may be considered if, in the opinion of the Hazard Sector Officer, no significant exposures have occurred and decontamination methods have been successful in reducing contamination levels to safe or acceptable concentrations.

Whenever it is known or suspected that a chemical has permeated PPE, the clothing should not be re-used.

All equipment used for decontamination must be decontaminated and/or disposed of properly. Buckets, brushes, clothing, tools and other contaminated equipment should be collected, placed in containers, and labeled. Also, all spent solutions and wash water should be collected and properly disposed of. Clothing that is not completely decontaminated should be placed in plastic bags, pending further decontamination and/or disposal.

Victim Decontamination

In addition to routine decontamination procedures, emergency decontamination procedures must be established. In an emergency, the primary concern is to prevent the loss of life or severe injury to civilians. If emergency treatment is required to save a life, complete decontamination may be delayed until the victim is stabilized and those providing care must be in appropriate protective clothing. If decontamination can be performed without interfering with essential life saving treatment or if a worker has been contaminated with an extremely toxic or corrosive material that could cause severe injury or loss of life, it must be performed immediately. If an emergency due to a hazmat-related illness develops, protective clothing should be removed from the victim as soon as possible to reduce the heat stress. During an emergency, provisions must also be made for protecting medical personnel and disposing of contaminated clothing and equipment.

Summary

Specific decontamination procedures will vary depending on the hazards involved and additional circumstances surrounding the incident. However, a detailed decontamination plan that can be easily adapted to a variety of conditions must be established prior to an entry team entering the Hot Zone. If is our hope and expectation that emergency responders who view "Decon Team" and participate in this training program will gain a clear understanding of the procedures necessary to decontaminate victims, equipment and fellow responders and to minimize contamination of the environment.

Decon Team by Emergency Film Group provides in-depth training for emergency responders on the process of decontamination at hazardous materials incidents. Another program, "Mass Decon", addresses decontamination for WMD incidents.