Tehran University of Medical Sciences International Journal of Occupational Hygiene 2008-5109 8 4 2017 04 05 208 216 EN ALI KARIMI Department of Occupational Health, School of public Health, Tehran University of Medical Sciences, Tehran, Iran SAMIRA ESLAMIZAD Food Safety Research Center, Shahid-Beheshti University of Medical Sciences, Tehran, Iran MARYAM MOSTAFAEE Department of Occupational Health, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran MAHIN HAGHSHENAS Occupational Health, Occupational and Environmental Health Administration office, Ministry of Health, Tehran, Iran MAHDI MALAKOUTIKHAH Department of Occupational Health, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran 2016 08 22 2017 04 05 Drivers are vulnerable to musculoskeletal and psychological disorders because of substantially harmful agents in this stressful occupation. This study aimed to investigate the influence of driver’s physical and psychological health on the risk of road accidents using fuzzy logic approach. Two input variables including musculoskeletal disorders (MSDs) and mental health, alongside accident risk levels as output variables were fuzzed using a fuzzy inference system (FIS). Triangular and trapezoid membership functions were used to graphically define outputs related to low, moderate, high and very high, in fuzzy sets. A Mamdani-type FIS was applied to represent all the rules in the IF-THEN format and the patterns of linguistic variables were designed using AND, OR and NOT operators. There was significant relationship between MSDs and psychological health with road accidents involving drivers of heavy vehicles (P<0.05). Besides, surface graphs illustrated the relationship between MSDs, psychological health and accident risks. FIS as a novel approach was used for predication of accident risk levels involving drivers of heavy vehicles based on health factors. Physical and psychological health can influence the safe operation of heavy vehicle drivers. The fuzzy inference system provided a method that is advantageous and with promising results for modeling of road accident risk levels on the basis of driver’s physical and mental health. https://ijoh.tums.ac.ir/index.php/ijoh/article/view/210 https://ijoh.tums.ac.ir/index.php/ijoh/article/download/210/313