Emergency exposure situations require prompt action in order to avoid or reduce adverse consequences. Uncertainty surrounding the ionising radiation types and exposure pathways is likely, particularly in the early stages of an emergency exposure situation. This factsheet provides an overview to protect emergency workers and helpers from exposure to ionising radiation during an emergency.
What do I need to know?
Your priorities in an emergency, as an emergency worker, are to regain control of the situation, mitigate consequences and save lives while ensuring your own safety. When an emergency involves a source of ionising radiation, it is termed an emergency exposure situation. In these situations, exposure to ionising radiation must be considered, normal occupational dose limits are no longer appropriate and guidance values are applied (ARPANSA RPS G-3).
What is the possible exposure?
Internal exposure to ionising radiation occurs when radioactive material is inhaled, ingested or enters into the bloodstream (e.g. through wounds). Internal exposure continues until the radionuclide either decays or is excreted from the body. In some cases, treatments can be administered to assist the body’s natural excretion processes.
External exposure can occur in two ways:
- contamination: when radioactive material is deposited on skin or clothes through immersion or airborne contaminants such as dust, liquids or aerosols. External contamination can often be removed from the body by simply removing contaminated clothing and washing exposed areas.
- irradiation: from being in close proximity to a radioactive source. Moving away from the source, limiting time spent near the source or increasing shielding between you and the source will reduce your exposure.
What are the possible health effects?
Table 1: Possible health effects
|Dose range (millisieverts)||Description||Possible health effects|
|Up to 10||Very low dose||None observed or expected (typical background range)|
|10–100||Low dose||Plausible health effects but not observed|
|100–1000||Moderate dose||Increase risk of cancer
Acute effects at higher end of range (above 500 mSv)
|Above 1000||High dose||Acute effects (burns, vomiting)
Death possible at very high doses (above 5000 mSv)
No health effects have been observed or are expected to be observed at the very low doses normally received in this occupation.
Ionising radiation has been proven to cause harmful short term effects at moderate and high doses received in short periods of time, above 500 mSv, with an increased risk of cancer shown to occur for long term exposures of above 100 mSv. These levels of exposure are possible in emergency management if identification and assessment is not undertaken to put relevant controls in place.
Who is responsible for your safety?
Organisations/employers are responsible for:
- designating you as an emergency worker at the preparedness stage
- enrolling you in an appropriate dosimetry program
- provision of monitoring equipment and PPE (see ‘Controls’ below)
- induction and ongoing training of emergency workers, including just in time training for helpers
Workers are responsible for:
- understanding the capabilities and limitations of their measurement systems
- complying with legitimate instructions of the employer or designated radiation safety officer
- participating in training, drills and exercises
Dose limit, reference level and guidance value
At the onset of an emergency exposure situation, the type and magnitude of ionising radiation exposure is unknown, and there is little scope to apply occupational dose limits. In the absence of dose limits, a national reference level of 50 mSv applies to emergency workers and helpers when responding to an emergency exposure situation. In emergency exposure situations, the dose guidance value of up to 500 mSv may be applied under circumstances in which the expected benefits to others clearly outweigh the emergency worker’s own health risks. These response actions should only occur on a voluntary basis, where the emergency worker understands and accepts the health risks and should not be undertaken by helpers. During the later stages of an emergency when the situation is under control, normal occupational dose limits should be applied.
Table 2: National reference level and guidance values for emergency workers and helpers in an emergency exposure situation
|20 mSv||Occupational dose limit||Long-term recovery operations|
|50 mSv||National reference level||Applied to most emergency workers and all helpers, and members of the public in an emergency exposure situation|
|500 mSv||Guidance value||Applied to emergency workers involved in urgent protective actions – including life-saving and prevention of serious injury or development of catastrophic conditions|
Personal Protective Equipment (PPE) is one of the most effective ways to reduce radiation exposure in an emergency, particularly respiratory protection to avoid internal exposure. Suitable protective clothing, i.e. chemical, biological and radiological (CBR) suits, will prevent external contamination. Coupled with appropriate monitoring, turn-back guidance and the application of the basic radiation safety principles (minimise time, maximise distance and use of shielding) to minimise doses.