Iranian Journal of Ergonomics

Background and Objectives: Studies have shown the effect of smoking on mental and cognitive performance of the individuals who need to concentrate on their work. The present study aimed to investigate the effect of smoking on cognitive performance of the automotive industry workers. 
Methods: In this case-control study conducted in 2018, 280 automotive industry workers were selected through the simple random sampling and then assigned to  two groups of smokers (100 cases) and non-smokers (180 controls). All the subjects were selected from the environments with the sound levels of 82 to 88 dB. The workers’ cognitive performance was also tested using the CPT, Stroop and Tower of London tests.
Results: The mean age of the case group was 36/02 (3/7) and that of the control group was 36/25 (3/65) years. The results showed that the scores of the TOL test in the case group (smokers) were lower than those of the non-smokers (OR=0/903, P<0.01), and other items of the TOL test had no significant relationship with the individuals’ smoking status (P>0/05). The Stroop and continuous performance tests also had a significant relationship with the individuals’ smoking status in terms of the number of correct responses and the response time as well as interference (P<0.01). Other items had no relationship with the individuals’ smoking status (P>0/05).
Conclusion: The results of this study showed that the use of cigarettes and nicotine substances significantly decreased the workers’ mental and intellectual performance, and smokers were more likely to suffer from concentration interference, low brain processing speed in decision-making, and low precision at work, compared to non-smokers.
 

Background and Objectives: Noise pollution is one of the most harmful physical factors in working environments in developed and developing countries, which has significant impacts on the workers’ quality of life. The aim of this study was to investigate mental and physiological effects of chronic exposure to noise.
Methods: This is a cross-sectional study carried out randomly in 2018 on 250 workers in the automotive Industry. To measure the subjects’ aggression and annoyance levels, the Buss and Perry’s Aggression Questionnaire was used as well as an annoyance questionnaire. In this study, blood pressure measurement was also done using ALPK2 mercuric pressure gauge.
Results: The results showed that there was a significant difference in the systolic and diastolic blood pressure and noise annoyance in the groups with a lower-than-85 and higher-than-85 dB sound pressure levels (P<0.001). Besides, the results of multivariate regression showed that the annoyance level and sound pressure level had a significant relationship with the workers’ blood pressure (P<0.01). Also, there was a significant correlation between aggression components and sound pressure level (P<0.01).
Conclusion: The results of this study clearly showed that chronic exposure to noise in work environments was associated with psychological and physiological changes, such as increased blood pressure and aggression levels. Hence, implementation of preventive programs can help reduce the incidence of the psychological and physiological disorders.