Decontamination Flashcards
Decontamination
or Decon is the process of removing or neutralizing contaminants that have accumulated on workers or equipment.
it is critical to worker health and safety at hazardous waste sites.
Decontamination protects all site personnel and reduces the spread of harmful materials into clean areas and helps prevent the mixing of incompatible chemicals.
Decon protects the community by preventing uncontrolled contaminants from leaving the site
Decontamination Plan
a decontamination plan should be developed before any work begins with hazardous substances on site. The plan is part of the health and safety program. It should include the following:
- 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 of disposing of clothing and equipment
SOP for Decontamination
SOP for Decon - the first step is to develop SOP’s
eg.
- minimize contact with hazardous substances
- use remote sampling
- protect equipment
- wear disposable outer garments
- use disposable equpment
Check PPE Before use
before each use the PPE should be checked to ensure that it doesnt have holes or punctions that would expose skin. Skin injuries such as cuts or 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 not be allowed to work onsite until the skin heals
Proper Dress out procedures
following proper procedures for deressing prior to entering the exclusion zone prevents contaminats for passing through the protective clothing and escape decontamination.
all fasteners zippers, snaps and buttons closed
gloves and boots should be tucked in
hoods should be worn out side the collar
rubber boots to protect the suit feet from tearing
doubling inner gloves
tough outer gloves over the rubber gloves
sleeves should be taped as well as all junctures
more ppe
must include an explanation of equipment selection and use, maintenance, disposal and storage, decontamination and disposal, training and proper fit , donning and doffing, inspection , in use monitoring program, evaluation, and equipment limitations
Training and retraining
all workers should be trained ton SOPs to minimize contact and maximize protection.
if there are any changes to the SOPs workers should be retrained and enforced as long as activities continue at the site
Levels of contamination
contaminants might be on the sureface of the PPE or permeated the material. if they have permeated the material and are not removed by decontamination they can continue to permeate to the inner surface and cause exposure. Surface contaminants are easy to detect and remove but contaminants that have permeated the surface can be difficult or impossible to detect or remove.
the degree of permeation are based on the following factors:
contact time concentration temperature size of contaminant molecules and pore space phjysical state of waste
Permeation factors
contact time. the longer a contaminant is in contact iwth an object the greater probability and extent of permeation. that is why minimizing the contact time is important in a decontamination program.
Concentration and Molecules
molecules flow from high areas of concentration to low areas of concentration. As concentration of wastes increase the possibility of permeation of PPE increases.
disposable ppe should be changed often and never reused.
an increase intemperature generally increases the permeation rate of contaminants
Size of contaminant molecules and pore material
Physical state of waste
permeation increases as the contaminant molecule become smaller and tthe pore space of the material to be permeated increases.
As a rule, gasses vapors and low viscosity liquids tend to permeate more readiloy than high viscosity liquids or solids. it can penetrate thorugh a zipper or around the cuff of a sleeve or pant leg.
seal these areas with tape using chemical resistant tape if desired.
upgrade to a fully encapsulated suit if the vapors are hazardous to the skin.
Decontamination Methods
many factors for decon - 2 facotrs
- if the decon method is effective for the specific chemicals and hazards
- if it poses health and or safety hazard
Methods of decontamination include:
isolation of contaminants
physical removal
chemical removal
Decontamination methods
Methods of decontamination Should either
isolate contaminants (dry decon )
physically remove,
inactivate contaminants by chemical reaction
remove contaminants by physical and chemical means
Isolation of Contaminants
Physical removal
dry decon
this process entails removing contaminated equipment and protective clothing and leaving it in the decontaminated area.
it is the simpliest to set up and it requires the least number of personnel.
physical removal
By rinsing or washing off contaminated areas decontamination can be completed.
contaminants that can be removed by physical means are:
loose contaminants can be removed (dust, and vapors that cling to equipment and workers that can be removed by water or a liquid rinse.)
adhering contaminants - glues cements resins mud have adhesieve properties and are difficult to remove
can be removed by solidyfying liquid or gel contaminants or by rinsing
Chemical removal
washing with cleaning solutions should follow physical removal of contaminants .
Cleaning solutions include
surfactants and
disinfectands that inactivate infectious agents
dry dust can be removed with hepa vacuum and work uniforms laundered in an approved facility
all workers are reuired to shower before leaving the site as well
Decontamination Solutions
the decontamination solutions used depend on the type of hazard. To determine the the best solution always seek expert assistance from manufacturers or medical specialists.
Simple dish soap and warm water remove the worst of contamination however other special methods are required depending on the contamination.
acid solutions such as nitrate acid and vinegar can be used to remove metal contamination from tools and equipment however care must be taken when handling these chemicals not to damage anything sensitive.
solvents such as hexane are required for cleaning equip contaminated such as oily mateirals.
extra ppe such as a face shield respirator and splash prtotection is required while mixing decon solutions.
bleach can be required for biological decontamination
disposal of decon solution s waste is planned and typically drummed and left on site for wate pick up
Testing for effectiveness
because decon methods vary in effectiveness.
Assess the following methods:
visual
wipe sampling
cleaning solution analysis
testing for permeation
Visual Observation
No reliable test. In some cases effectiveness can be determined by visual observation
Natural Light
Discolorations stains corrosive effects visible dirt alteration ins clothing fabric
However not all contaminants leave visible traces - many of the solutions that can contaminate clothing are not easily observed
Ultraviolet Light
certain contaminants - polycyclic aromatic hydrocarbons (common to Refined oil and solvent waste.) flouresce and can be visually detected when exposed to ultraviolet light can be used to determine contamination of skin, clothing and equipment - certain areas of the skin can flourese naturally
the use of can increase the risk of skin cancer and eye damage. so it must be accessed if the ultraviolet light prior to it’s use at a waste site.
Wipe Sampling
After the fact information on the effectiveness of decontamination
a dry or wet cloth is wiped over the surface of a contaminated subject and then analyzed in a laboratory
outer and inner surface of protected clothing should be tested.
skin can also be tested using wipe samples
Decontamination Procedures
a component of the site specific health and safety plan HASP and must be developed communicated anf implemented to employees before entering a hazardous work site. The site safety and health officer must require and monitor decontamination of the employee decontamination and disposal of the employee’s clothing and equipment
As well as the substances used for decontamination before the employee leaves the work area.
Cleaning solution analysis
Testing for Permeation
Cleaning solution analysis
to test the effectiveness of deconis to analyze the residue of contaminants left in the cleaning solutions elevated elements of contamination in the final rinse solution suggests additional cleaning and rinsing are needed.
Testing for permeation
pieces of the protective garments be sent to a laboratory for analysis.
Showers
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 job can take 6 months or greater.
must not remove protective equipment or clothing from change rooms
