ON THE ISSUE OF RADON EXPOSURE IN THE EXISTING RADIATION SITUATION AT WORKPLACES
Authors:   State Institution «O.M. Marzіeiev Institute for Public Health of the National Academy of Medical Sciences of Ukraine», Pavlenko T. O. , Fryziuk M. A. ,   State Institution «O.M. Marzіeiev Institute for Public Health of the National Academy of Medical Sciences of Ukraine», Tarasiuk O. Ye. ,   State Institution «O.M. Marzіeiev Institute for Public Health of the National Academy of Medical Sciences of Ukraine»
Published: December 2024

Objective: assessment of probable exposure levels from radon and NORM in workplaces within the context of justifying radiation protection plans in an existing exposure situation.
Materials and methods. Materials regarding the assessment of naturally occurring radioactive material (NORM) content in tailing from mining and processing industries in Ukraine and assessments of contamination levels of industrial sites of oil and gas enterprises were used for estimating the probable range of effective doses (ED) of workers from NORM at industrial enterprises. These materials were obtained as a result of research conducted by specialists from the Radiation Protection Laboratory of the State Institution «O.M. Marzіeiev Institute for Public Health of the National Academy of Medical Sciences of Ukraine» (RP SI «IPH NAMSU»). The results of studies conducted by the State Institution «Ukrainian Scientific Research Institute of Industrial Medicine» (SI «UKRMEDPROM») were used for calculating the EDs of iron ore miners. Calculations of probable EDs of industrial enterprise workers were carried out using methodologies and recommendations from publications of the IAEA related to occupational exposure. Assessments of exposure levels for office workers were based on measurements of indoor radon concentrations of first-floor premises in multi-story buildings of industrial urban development from the laboratory’s own databases. Radon measurements in indoor air were conducted using passive track etch radon detectors with an exposure time of at least 30 days. Calculations of EDs for office workers were carried out using dose coefficients and mathematical models from the ICRP.
Results. When workers are exposed to radon as a result of the technological process, radiation exposure is limited by dose criteria. Using non-uranium miners as an example, it was shown that effective doses (ED) due to gamma radiation varied within a narrow range, ranging from 0.2 to 0.4 mSv/year, and were on average an order of magnitude lower than the radon component of the total ED for the two groups of mines, which amounted to 2.0–14.0 mSv/year for the Northern group and 0.3–0.8 mSv/year for the Southern group. For three underground worker specialties, radiation EDs could potentially exceed the reference level of 6 mSv/year and fall under regulatory control. Potential radiation EDs for workers at one of the Ukrainian oil fields were generally not significant (<0.1–1 mSv/year), except for areas where used pipe storage and sludge settlers were located (70.0 mSv/year; 28.0 mSv/year at a distance of 10 meters), near which dose limits for Category A personnel (6 mSv/year), falling under regulatory control, were exceeded. Radon exposure in workplaces also includes the presence of workers in regular office premises on the first floors of multi-story buildings, where the main source of radon entry into the air is the underlying soil. For the most researched regions of Ukraine (~1200 measurements of radon activity concentrations in first-floor premises), it was found that the reference level of 300 Bq/m3 is exceeded in 0.2–0.5% of cases in certain regions, indicating that potentially the reference level may be exceeded in tens of thousands of premises.
Conclusions. A differentiated approach is justified for assessing the hazards of workplaces, allowing for optimizing radiation protection for workers at a reasonable cost and saving significant resources for enterprises. Effective doses (ED) of radiation for workers at enterprises where radon is an integral part of the technological process vary widely and can differ by an order of magnitude even within the same enterprise. Reference levels of 300 Bq/m3 may be exceeded in tens of thousands of office premises, and only through direct measurements of radon activity concentrations in building air can such premises be identified.
Key words: indoor radon; existing exposure situations; exposure in workplaces; effective exposure dose of workers.