© The Author(s) 2020. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com Radiation Protection Dosimetry (2020), pp. 1–8 doi:10.1093/rpd/ncaa101 ESTIMATION OF THERMAL POWER PLANT WORKERS EXPOSURE TO MAGNETIC FIELDS AND SIMULATION OF HAZARD ZONES Majid Bagheri Hosseinabadi 1 , Narges Khanjani 2 , Mohammad Hossein Ebrahimi 3 and Jamal Biganeh 1, * 1 School of Public Health, Shahroud University of Medical Sciences, Shahroud, Iran 2 Environmental Health Engineering Research Centre, Kerman University of Medical Sciences, Kerman, Iran 3 Environmental and Occupational Health Research Center, Shahroud University of Medical Sciences, Shahroud, Iran *Corresponding author: jamal.biganeh@gmail.com Received 1 May 2020; revised 20 June 2020; editorial decision 23 June 2020; accepted 23 June 2020 Extremely low-frequency magnetic fields (ELF-MFs) have raised some concerns due to their possible effects on workers’ health. In this study ELF-MFs were measured in different units of the thermal power plant based on gridding the indoor space. The exposure level was measured by spot measurement based on the IEEE Std C95.3.1 and then simulated in units with the highest magnetic field intensity by using ArcGIS software. The operators and balance of plant (BOP) technicians (12.64 ± 9.74 μT) and office workers (2.41 ± 1.22 μT) had the highest and lowest levels of both measured and estimated ELF-MFs exposure. The highest measured ELF-MFs were in the vicinity of the power transmission lines in the transformers’ building (48.2 μT). Our simulation showed the high and low exposure areas and ranked exposure well; but, the actual measurements of ELF-MFs exposure were in all cases higher than the estimated values, which means we still need to improve our estimations. INTRODUCTION In recent decades, people have been exposed to extremely low-frequency magnetic fields (ELF- MFs) generated by power transmission lines and home appliances, in industrial and residential environments ( 1) . These fields may cause adverse biological and biochemical effects and have raised a lot of concern. Based on the results of epidemiological studies, the International Agency for Research on Cancer has classified magnetic fields as potential carcinogens for humans (group 2B), due to the increased risk of childhood leukemia observed with exposure to these fields ( 2) . These fields may also affect cell reproduction, cell membrane structure, gene expression and apoptosis and cause DNA damage in peripheral blood mononuclear lymphocytes ( 3, 4 ) . Other studies have demonstrated that these fields decreased sleep quality and caused depression, stress and anxiety among exposed workers ( 5, 6) . These fields may also disrupt the radical pairing mechanisms by interacting with the spin of unpaired electrons and cause increase in the concentration of free radicals ( 7, 8 ) . Among the various job groups, power plant work- ers are significantly exposed to these fields, due to their closeness to power generation equipment and transmission lines, and this increases the likelihood of adverse health effects among these workers. Thus, it is crucial to take measures aimed at reducing exposure to ELF-MFs. Some guidelines have been published about the safe thresholds of job exposure to ELF- MFs. For example, the International Commission on Non-Ionizing Radiation Protection has suggested a reference value for job exposure to magnetic fields, which is 1000 μT ( 9 ) . The basic characteristics of ELF- MFs are related to their wavelength and field polar- ization. These features are also known as the near- and far-field regions of exposure. The magnetic fields in working environments where workers are exposed to high levels are usually near fields ( 10 ) . It has been shown that the mean of workers expo- sure to magnetic fields in the power plant industry can be 0.8–1.4 μT for workers in substations, 0.18–1.72 μT for workers at power stations, 0.03–4.57 μT for workers in lines and cables units and 0.2–18.47 μT for electricians ( 11 , 12 ) . Ozen ( 13 ) measured magnetic fields inside a 380/154 kV substation under normal load conditions. The maximum level of magnetic fields in the outdoor of this station was about 20 μT and inside the control room was 65 μT. Moreover, Korpinen et al . reported that the mean level of magnetic fields in 110 kV transforming and switching stations were 28.6 μT (standard deviation (SD) = 95.9) ( 14) . In another study, occupational exposure to electric and magnetic fields during various job tasks at 110 kV substa- tions was measured. In these substations, workers Downloaded from https://academic.oup.com/rpd/advance-article/doi/10.1093/rpd/ncaa101/5890834 by guest on 13 August 2020