Fixed Contamination - contamination that can not be readily removed from surfaces.
Detected by using direct frisking of the item with a contamination monitoring instrument such as an ASP-1 with a GM “Pancake” probe.
Removable Contamination - contamination that can be readily removed from surfaces where it is located.
It may be transferred by casual contact (wiping, brushing, or washing)
Detected by swiping the area with a small round piece of filter paper and then counting the contamination on the paper with a contamination monitoring instrument.
Airborne Contamination - contamination suspended in air. Much like smoke, the danger is from inhalation.
Radiation Protection Specialists have equipment designed to sample the air for airborne contamination
Air is pulled through a filter paper, and the paper is counted using a contamination monitoring instrument
Internal Dose
Internal dose results from radioactive material being taken into the body through:
Ingestion - Liquids and finely divided solids are easily transferred to the mouth.
Inhalation - Airborne particulates, vapors, and gases may enter by nose and mouth.
Absorption - Contaminants may diffuse through the skin
Injection - Contaminants may enter via open or scabbed wounds
Health Risk from Airborne Contamination
Analogy: Airborne contamination is like smoke. Some smoke, like that from a burning building, poses an immediate health hazard. Other smoke, like that from a burning cigarette, poses a long-term health hazard.
The types of airborne contamination experienced at Chernobyl created an immediate health hazard (from skin and lung doses) to those workers who were exposed to it.
First responders may have to deal with various types and levels of airborne contamination.
Determine the types and levels of airborne contamination ASAP so appropriate actions can be taken.
Methods to Reduce Internal Dose
Reducing the potential for radioactive materials to enter the body is important.
Methods to prevent intake:
Wearing respiratory protection
Not eating, drinking, chewing or applying cosmetics in contaminated areas
Sealing the openings of protective clothing with tape
keeping wounds protected and clean
Respiratory Protective Equipment
Respiratory protection (e.g., air-purifying respirator, Self-Contained Breathing Apparatus) is used to prevent the inhalation of radioactive materials.
Respiratory protection should be used when entering an area where airborne contamination is likely.
Remember, airborne contamination is like smoke. In most Airborne Radioactivity Areas, the hazard is comparable to cigarette smoke. In the case of a fire or explosion, the hazard could be much greater.
If you suspect you may have become contaminated, contact a Radiation Protection Specialist (if possible) before removing your protective equipment..
In an emergency, if a Radiation Protection Specialist is not available and you must remove your mask or change your air supply, wipe it off with a damp cloth prior to removing the mask.
Emergency Respiratory Protection
Man’s cotton handkerchief, 16 thickness - 94 %
Man’s cotton handkerchief, 8 thickness - 88 %
Toilet paper, 3 thickness - 91 %
Bath towel, 2 thickness - 85 %
Cotton shirt, 2 thickness - 65 %
Ref. U.S. Army Chemical Corps
Internal Monitoring Methods
Accidental intake of radioactive material (i.e., internal contamination) can cause dose to the whole-body or to individual organs.
If there is any reason to suspect that radioactive material might have been taken into the body, internal dosimetry is used to determine if any internal contamination has occurred.
Two types of internal dosimetry:
“In-Vivo Monitoring”
“In-Vitro Monitoring”
In-Vivo Monitoring
In-vivo monitoring measures the amount of internally deposited radioactive material by taking a measurement outside the body.
In-Vitro Monitoring
In-vitro monitoring (or “bioassay”) measures the amount of internally deposited radioactive material by the analysis and evaluation of bodily fluid (e.g., urine) or other material excreted or removed from the human body.
First responders will be tested only if a reason exists to suspect an intake, or if a test is requested.
Inside Radiological Areas
While inside a Radiation Area, keep your dose ALARA using time, distance, and shielding
When inside a Contamination Area, exit as soon as possible if a wound or a breach in your protective clothing occurs
While inside an Airborne Radioactivity Area, do not remove your respirator unless continuing to wear it will cause personal injury
Exiting Radiological Areas
When leaving a Contamination Area, monitor personnel and equipment for contamination as soon as possible after the emergency is under control
When exiting an Airborne Radioactivity Area, do not remove your respirator until you have been monitored for contamination. If you must remove the respirator prior to surveying it, wipe it down using a damp cloth first
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