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A restricted area is defined as an area, access to which is limited by the licensee for the purpose of protecting individuals against undue risks from exposure to radiation and/or radioactive materials. These areas are indicated by the radiation symbols which are usually on the door to a lab, where radioactive materials are used, or an area where a radiation source is present. (See the attached pictures of these symbols).
When you enter a restricted area, any dose of radiation you may receive will be classified as an "Occupational Dose". The definition of occupational dose is the dose received by an individual in a restricted area in the course of employment in which the individual's assigned duties involve exposure to radiation, from licensed and unlicensed sources of radiation, whether in possession of the license or not. Occupational dose does not include background radiation.
It is important to understand that, with the exceptions given in the definition of occupational dose, any dose received by any individual in a restricted area is an occupational dose. The annual occupational dose for an adult is 5 rem, and for minors, 0.5 rem.
Ionizing radiation means alpha particles, beta particles, gamma rays, X-rays, neutrons, high speed electrons, high speed protons, and other particles capable of producing ions. At all times, the amount of radiation received by an individual is to be kept -- As Low As Reasonably Achievable (ALARA). This means making every effort to maintain exposures to radiation as far below the dose limits as practical, consistent with activities of the licensee. The licensee undergoes annual audits and must defend their results and methods of carrying out ALARA.
It is possible that a pregnant employee may encounter a restricted area in the course of designated work. A pregnant worker can make a declaration in writing of her pregnancy to her supervisor and the Radiation Safety Officer of the Campus, and will be provided with special monitoring devices during the course of pregnancy to ensure that her exposure does not exceed 10% (0.5 rem) of that normally allowed for adult workers (5 rem). This declaration is fully optional to the individual involved.
Workers who may be subjected to radiation exposure should be made aware of the health risks. Radiation, such as X-rays or gamma rays, that interact with living tissue may deposit enough energy to cause biological damage. Radiation can cause several different types of events, such as the very small displacement of molecules, the changing of a molecule to a different form, or the removal of electrons from atoms or molecules. When a quantity of radiation energy deposited in living tissues is high enough, biological damage can occur as a result of chemical bonds being broken and cells being damaged or killed. These effects can result in observable clinical symptoms.
It should be pointed out that radiation hazards on University of Maryland, College Park Campus are readily observable by the use of radiation signs, lights indicating radiation hazards, and in some cases, Klaxon horns to warn of radiation producing equipment about to be placed into operation. These signs, lights, and horns should be observed by the workers in the course of their designated work requirements, and the warnings followed without question.
University of Maryland Radiation Safety Staff are available to help in determining where a hazard may be of sufficient danger to indicate where additional precautions may be warranted. [Phone (301) 314-8336].
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