HAZWOPER 40 - Lesson 10: Decontamination
Decontamination Plan
A decontamination plan should be developed before any operations begin with hazardous substances. The Decontamination Plan is part of the site health and safety program. The decontamination plan should: Establish methods and procedures Determine appropriate decon methods Determine number and layout of decon stations Establish procedures to prevent contamination of clean areas Determine decon equipment needed Establish methods for disposing of clothing and equipment
Permeation Factors - Temperature
An increase in temperature generally increases the permeation rate of contaminants.
Cleaning Solution Analysis
Another way to test the effectiveness of decontamination procedures is to analyze for contaminants left in the cleaning solutions. Elevated levels of contaminants in the final rinse solution can suggest that additional cleaning and rinsing are needed.
Permeation Factors - Physical State of Wastes
As a rule, gases, vapors, and low-viscosity liquids tend to permeate more readily than high-viscosity liquids or solids. Often times it can penetrate through a zipper or around the cuff of a sleeve or pant leg. Seal these seems with tape that is appropriate for the materials at hand, using chemical resistant tape if required. Upgrade to a fully-encapsulating suit if the vapors or gases are hazardous to the skin.
Testing for Effectiveness
Because decontamination methods vary in their effectiveness, the decontamination method should be assessed. Some ways to assess effectiveness are: Visual observation Wipe sampling Cleaning solution analysis Testing for permeation
Check PPE before Use
Before each use, the personal protective equipment (PPE) should be checked to ensure that it contains no cuts or punctures that could expose a worker's skin to wastes. Skin injuries, such as cuts and scratches, may allow penetration into the body by chemicals or infectious agents that directly contact the worker's skin. Particular care should be taken to protect these areas. Workers with large areas of damaged skin should be kept from working on-site until their skin heals.
Ultraviolet Light
Certain contaminants, such as polycyclic aromatic hydrocarbons (which are common in many refined oils and solvent wastes) fluoresce and can be visually detected when exposed to ultraviolet light. Ultraviolet light can be used to observe contamination of skin, clothing, and equipment; however, certain areas of the skin may fluoresce naturally, making a visual test uncertain. In addition, use of ultraviolet light can increase the risk of skin cancer and eye damage; so, a qualified health professional should assess the benefits and risks associated with ultraviolet light prior to its use at a waste site.
Levels of Contamination
Contaminants might be either on the surface of the PPE or may have permeated through the PPE material. If contaminants that have permeated a material are not removed by decontamination, they can continue to permeate to the inner surface and cause an unexpected exposure. Surface contaminants are easy to detect and remove, but contaminants that have permeated the surface can be very difficult or impossible to detect or remove. The degree of permeation depends on a number of factors including: Contact time Concentration Temperature Size of contaminant molecules and pore space Physical state of wastes
Lesson Focus This lesson focuses on the following topics:
Decontamination Decontamination Plan Levels of Contamination Decontamination Methods Testing for Effectiveness Decontamination Facility Design Decontamination Selection Emergency Decontamination
Decontamination Facility Design
Decontamination facilities should be located in the contamination reduction zone (CRZ), the area between the exclusion zone (the contaminated area) and the support zone (the clean area). There are several levels of decontamination procedures that depend on a number of site-specific factors. Procedures should provide an organized process reducing the levels of contamination, and each procedure should be performed at a separate station in order to prevent cross contamination. The sequence of stations is called the decontamination line.
Health and Safety Hazards of Decontamination
Decontamination itself can pose hazards under certain circumstances. Decontamination methods may be incompatible with hazardous substances or with the clothing or equipment being decontaminated. Use the Quick Selection Guide to Chemical Protective Clothing to find the chemical and physical compatibility of components to ensure maximum decontamination effectiveness.
Decontamination Procedures
Decontamination procedures are a component of the site specific health and safety plan (HASP) and, consequently, must be developed, communicated to employees, and implemented before employees enter a hazardous waste site. As necessary, the site safety and health officer must require and monitor decontamination of the employee and decontamination or disposal of the employee's clothing and equipment, as well as the substances used for decontamination, before the employee leaves the work area.
Decontamination
Decontamination, or decon, is the process of removing or neutralizing contaminants that have accumulated on workers and equipment. It is critical to worker health and safety at hazardous waste sites. Decontamination protects all site personnel by reducing the transfer of harmful materials into clean areas and helps to prevent the mixing of incompatible chemicals. Decontamination also protects the community by preventing uncontrolled transportation of contaminants from the site.
Natural Light
Discolorations, stains, corrosive effects, visible dirt, or alterations in clothing fabric can indicate that contaminants have not been removed. However, not all contaminants leave visible traces; many contaminants that can permeate clothing are not easily observed.
Proper Dress-Out Procedures
Following proper procedures for dressing prior to entering the exclusion zone (i.e., restricted zone) reduces the potential for contaminants to bypass the protective clothing, and escape decontamination. In general, all fasteners should be used (i.e., zippers fully closed, all buttons closed, all snaps closed). Gloves and boots should be tucked under the sleeves and legs of outer clothing, and hoods (if not attached) should be worn outside the collar. Another pair of tough outer work gloves are often worn over the disposable inner gloves which tend to tear easily. Doubling up on inner gloves is also a good idea for added protection. Wearing rubber overboots is also a good idea because the suit feet quickly tear out, All junctures should be taped to prevent contaminants from getting inside the gloves, boots, and jackets (or suits, if a one-piece construction). The PPE program must include an explanation of equipment selection and use, maintenance and storage, decontamination and disposal, training and proper fit, donning and doffing procedures, inspection, in-use monitoring, program evaluation, and equipment limitations.
Introduction
Hazardous workplaces must have decontamination plans in place as part of a more comprehensive site health and safety program before actual operations begin. Decontamination procedures are a component of a site-specific health and safety plan (HASP) and must be developed and directly communicated to workers. Protective clothing and equipment must be decontaminated, cleaned, laundered, maintained, and replaced when no longer useful. Under certain circumstances, decontamination itself can cause concerns, for instance, with reactive substances, so care must be taken to understand potential dangers and avoid them altogether.
Emergency Decontamination
In addition to routine decontamination procedures, emergency decontamination procedures must be established. In an emergency, the primary focus is to prevent the loss of life or severe injury. Decontamination should not interfere with essential life saving tasks. Provisions should also be made to protect medical personnel from contamination.
Physical Removal
In many cases by rinsing or washing off contaminated areas, decontamination can be completed. Contaminants that can be removed by physical means include: Loose contaminants - dusts and vapors that cling to equipment and workers that can be removed with water or a liquid rinse. Adhering contaminants - contaminants such as glues, cements, resins, and mud that have adhesive properties and are difficult to remove can be removed by solidifying liquid or gel contaminants or by rinsing.
Training and Retraining
Initially, all workers should be trained on the SOPs to minimize contact and maximize protection. If any significant changes are made to the SOPs, workers should be retrained. These procedures should be enforced as long as activities continue at the site.
Decontamination Methods
Many factors influence the selection of a decontamination method. Two factors must be taken into consideration: If the decontamination method is effective for the specific substances present If the method itself poses any health or safety hazards. Methods of decontamination include isolation of contaminants, physical removal, and chemical removal. Decontamination methods should either: Isolate contaminants (dry decon) Physically remove contaminants Inactivate contaminants by chemical action Remove contaminants by a combination of both physical and chemical means
Permeation Factors - Concentration
Molecules flow from areas of high concentration to areas of low concentration. As concentrations of wastes increase, the potential for permeation of personal protective clothing increases. Disposable PPE should be changed often as it becomes contaminated and never re-used.
Learning Objectives At the completion of this lesson, you will be able to:
Name the six points a decontamination (decon) plan should address. List six Standard Operating Procedures (SOPs) for decontamination that minimize contact with waste and the potential for contamination. Identify five factors that may affect the degree of permeation. Discuss the two factors that must be taken into consideration in selecting a decon method. Compare and contrast decon steps by PPE level. Describe a basic six-step decontamination line.
Permeation Factors - Size of Contaminant Molecules and Pore Space
Permeation increases as the contaminant molecule becomes smaller, and as the pore space of the material to be permeated increases.
Basic Six-Step Decontamination Line What follows is an example of a basic six-step decontamination line. As stated earlier, each step should be separated physically to prevent cross contamination and should be arranged in order of decreasing contamination.
Station 1 - Equipment drop Station 2 - Wash and rinse boots and gloves, and outer garment Station 3 - Air tank change (NOTE: this is the last step if worker returns to Hot Zone.) Station 4 - Boots, gloves and outer garment removal Station 5 - SCBA face-piece removal Station 6 - Field wash
Level C Decontamination Line
Step 1: Segregated equipment drop Step 2: Boot cover and glove Step 3: Boot cover and glove rinse Step 4: Tape removal - boot Step 5: Boot cover removal Step 6: Outer glove removal Step 7: Suit/safety boot wash and rinse Step 8: Safety boot removal Step 9: Fully-encapsulating suit and hardhat removal Step 10: Inner glove wash and rinse Step 11: Face piece removal Step 12: Inner glove removal Step 13: Inner clothing removal Step 14: Field wash More About: www.osha.gov/publications/complinks/osshg-hazwaste/append.pdf
Decontamination Steps by PPE levels Level A Decontamination Line
Step 1: Segregated equipment drop Step 2: Boot cover and glove Step 3: Boot cover and glove rinse Step 4: Tape removal - boot Step 5: Boot cover removal Step 6: Outer glove removal Step 7: Suit/safety boot wash and rinse Step 8: Safety boot removal Step 9: SCBA backpack removal Step 10: Fully-encapsulating suit and hardhat removal Step 11: Inner glove wash and rinse Step 12: Face-piece removal Step 13: Inner glove removal Step 14: Inner clothing removal Step 15: Field wash
Level B Decontamination Line
Step 1: Segregated equipment drop Step 2: Boot cover and glove Step 3: Boot cover and glove rinse Step 4: Tape removal - boot Step 5: Boot cover removal Step 6: Outer glove removal Step 7: Suit/safety boot wash and rinse Step 8: Safety boot removal Step 9: SCBA backpack removal Step 10: Fully-encapsulating suit and hardhat removal Step 11: Inner glove wash and rinse Step 12: Face-piece removal Step 13: Inner glove removal Step 14: Inner clothing removal Step 15: Field wash
Testing for Permeation
Testing for the presence of permeated chemical contaminants requires that pieces of the protective garments be sent to a laboratory for analysis. If an employee's non-impermeable clothing becomes grossly contaminated with hazardous substances, the employee must immediately remove that clothing and take a shower. Impermeable protective clothing must be decontaminated before being removed by the employee. Protective clothing and equipment must be decontaminated, cleaned, laundered, maintained, or replaced to retain its effectiveness. The employer must inform anyone who launders or cleans such clothing or equipment of the potentially harmful effects of exposure to hazardous substances. Employees who are required to shower must be provided showers and change rooms that meet the requirements of 29 CFR 1910.141, Subpart J - General Environmental Controls. HAZWOPER requires showers and change rooms when a hazardous waste cleanup operation will take six months or longer to complete. In addition, unauthorized employees must not remove their protective clothing or equipment from change rooms unless authorized to do so. More About: Chapter 10 of the Occupational Safety and Health Guidance Manual for Hazardous Waste Site Activities ("4-Agency Manual") provides more information on decontamination procedures, and Appendix D of the manual offers example decontamination layouts for levels A, B, and C. TSD facilities are also required to implement some of the same requirements specified for hazardous waste sites. Paragraph (p) of HAZWOPER references several sections within paragraphs (b)-(o), for instance: • Medical surveillance program 1910.120(p)(3) references 1910.120(f). • Decontamination program 1910.120(p)(4) references 1910.120(k).
Decontamination Solutions
The decontamination solution used will be dependent on the type of hazard. These solutions are provided as recommendations. In order to determine the best solution for a particular situation, always seek expert assistance from manufacturers or medical specialists. Simple dish soap and warm water often removes the worst of the contamination, however other special solutions may be required. Acid solutions such as nitric acid or vinegar can be used to removed metals contamination from tools and equipment, however care must be taken when handling these chemicals not to damage anything sensitive. Solvents such as Hexane are also required for cleaning equipment contaminated with oily materials. Sometimes extra PPE such as a face shield, respirator, and splash protection is required while mixing decon solutions. Bleach may also be required for biological decontamination. Dispoosal of decon solutions and wastes must also be planned for. It is typically drummed and left on-site for pick-up with the rest of the the waste. Decontamination Solutions: https://player.360training.com/ICPFileSystem/PersistentAssets/160745/280586/DECONTAMINATION_SOLUTIONS.pdf
Standard Operating Procedures for Decontamination
The first step in decontamination is to establish standard operating procedures (SOPs) that minimize contact with waste and the potential for contamination. Some examples of SOPs include: Minimize contact with hazardous substances Use remote sampling Protect equipment Wear disposable outer garments Use disposable equipment
Permeation Factors - Contact Time
The longer a contaminant is in contact with an object, 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
Visual Observation
There is no reliable test to immediately determine how effective decontamination is. However, in some cases, effectiveness can be estimated by visual observation.
Lesson Description
This lesson, Decontamination, explains how to establish a site decontamination plan and the importance of such a plan. Decontamination is the process of removing or neutralizing contaminants that have accumulated both on workers and on equipment at a waste site. The lesson emphasizes the importance of evaluating the levels of contamination present onsite so that the appropriate decontamination methods can be selected and standard operating procedures established. Finally, how to design a decontamination facility to control the various levels of exposure found onsite is covered, along with a detailed review of decontamination line processes and the importance of emergency preparedness.
Isolation of Contaminants (Dry Decon)
This process entails removing contaminated equipment and protective clothing and leaving it at the decontamination area. This is the simplest decontamination procedure to set up and it requires a minimum number of personnel.
Chemical Removal
Washing with cleaning solutions should follow physical removal of contaminants. Examples of cleaning solutions include surfactants that reduce adhesion forces and disinfectants that inactivate infectious agents. The worst of dry dust can often be removed from clothing with a HEPA vacuum(so as not to blow the dust back into the air) and work uniforms laundered in an approved facility. All workers are often required to shower before leaving the site as well.
Wipe Sampling
Wipe testing provides after-the-fact information on the effectiveness of decontamination. In this procedure, a dry or wet cloth, glass fiber filter paper, or swab is wiped over the surface of the potentially contaminated object and then analyzed in a laboratory. Both the inner and outer surfaces of protective clothing should be tested. Skin can also be tested using wipe samples. Radioactive decontamination can be measured with an instrument. The worker may not leave the site until the instrument clears the worker without counting too much radiation above background levels.
One way to test the effectiveness of decontamination procedures is to _________.
analyze for contaminants left in the cleaning solutions.
Decontamination Selection Various methods for decontamination can be used. Each scenario is different, so decontamination selection should be evaluated on a case-by-case basis. Some factors to take into consideration include:
• Equipment selection: When selecting equipment, consider whether the equipment should be decontaminated, or if it should it be discarded. • Disposal methods: All equipment used for decontamination should be disposed of properly (example: using plastic bags). • PPE for decontamination personnel: The levels of protection will vary with the level of decontamination and where workers are assigned. For example, someone in the exclusion zone may need higher protection from PPE than someone working in the CRZ.
