Anything to do with radiation and radioactive materials strikes fear into the hearts of many people, since they tend to be couched in terms of something abnormal and life-threatening. In fact, radiation is as much a part of nature as we ourselves are, and enjoys extensive use in medicine, science and industry.
The task of the Radiation Department of the Environmental Board is to protect people and the environment from the dangerous effects of ionising radiation. It is also required to ensure that radiation safety and protection are enacted at a level which enables human exposure to be kept to a reasonable minimum. The department fulfils its tasks through the organisation of radiation protection and the performance of radiation monitoring. Its third key are of operations is guaranteeing readiness to respond to a radiation emergency.
The field of use of sources of radiation is extensive. X-ray equipment is used in human and veterinary medicine to diagnose illnesses; in customs to check baggage; in the machine industry to monitor the quality of welded joints; in the regulation of technological processes; in assessing the quality of road surfaces; and in scientific biological studies.
In the field of radiation protection our clientele comprises almost seven hundred companies and institutions using sources of ionising radiation. All of them require a radiation practice licence for their operations. The task of the Radiation Department is to make sure that the employees of a company applying for or holding such a licence are able to use radiation equipment safely. It also checks that workers and residents who come into contact with radiation are not exposed to unnecessary doses. Employees who work with radiation carry dosimeters, which help them monitor the level of radiation to ensure that it does not exceed the norm.
The state of the environment is constantly scrutinised as part of the national radiation monitoring programme, with laboratory analyses being carried out of the radioactivity of the maritime environment, water, ambient air, food and milk. In addition to state monitoring, the laboratory also determines the level of radioactivity in building materials and surface and other samples and measures radon levels inside buildings.
Almost half of all radiation from natural sources comes from the radon which enters buildings from the ground beneath it. In its work with the Geological Survey of Estonia in carry out measurements, the Environmental Board has produced a radon risk map which indicates the levels of radon in different areas. Since high levels of radon can lead to health problems, we recommend that people take the chance of radon risk into account when building or renovating houses. If measurements indicate a high level of radon, a variety of construction means can be employed to reduce it.
In line with national legislation and international agreements, the Environmental Board carried out constant monitoring of the level of radiation in the natural environment. We immediately inform the relevant agencies in Estonia and our international partners of any radiation incidents. A network of automated stations measuring gamma radiation has been set up across Estonia for the early detection of radiation incidents, for example the spread of radioactive pollution caused by a nuclear accident in a neighbouring country. Samples are also collected from three air filtration stations to analyse the radioactivity of airborne particles.
If a station registers a rise in the level of radiation, notification is automatically sent to the Radiation Department, which then analyses the cause. The early warning system works in such a way that the International Atomic Energy Agency and the radiation centres in neighbouring countries are also immediately informed of such changes.
If the rise in the level of radiation has been caused by a cloud of radioactive material, the movement of the cloud and the spread of the material can be forecast in association with the Estonian Meteorological and Hydrological Institute and the University of Tartu. Potential crisis response operations – which in the worst case scenario would involve evacuating the population – would be organised by the Rescue Board.
The list of X-ray equipment used in hospitals and other medical facilities is rather long: mammographs, radiographs, fluoroscopes, angiographs, X-ray image intensifiers (C-arms), orthopantomographs and dental X-ray equipment. Before a radiation practice licence is issued, checks are carried out into the skills and knowledge of the people who will be using the equipment as well as into the equipment itself and the structural features of the room in which it will be situated.
On the one hand, hospital staff must be able to handle the equipment in the appropriate way. They must be aware of the working principles of the equipment and be able to protect themselves from the radiation they emit. Staff working within the field of radiation wear specially designed clothing made of lead, including gloves, aprons, skirts and vests. They also carry personal dosimeters which measure the dose of radiation they are exposed to each day.
On the other hand, the location of the radiation equipment must meet certain requirements. Those working with the equipment and the people in the adjoining rooms must be protected. To make sure that this is the case, the radiation resistance of these rooms is checked regularly. In the event, for example, that a wall does not provide adequate protection while a piece of radiation equipment is in use, it must be reinforced so that it does provide sufficient resistance.
Photo: Uko Rand