Iran Occupational Health

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Abstract
Background and aims: Regarding development of several thermal indices and limitations of these indexes, in this research we were examined the applicability and validity of Modified discomfort index (MDI) in Outdoor occupational environments.
Methods: This cross-sectional study was done on 175 subjects in summer (2016) in 12 mines construction materials of Tehran Province. Environmental and Physiological parameters (oral temperature, tympanic temperature and skin temperature) were measured simultaneously at three periods; also Modified discomfort index (MDI) together with three other Direct Indices include Wet-bulb globe temperature (WBGT), Oxford index (WD) and Wet-bulb dry temperature (WBDT) were calculated. For survey of applicability and validity of Modified discomfort index, the correlation between this index and other Direct Indices at different times of day with Physiological parameters was determined through the Pearson correlation coefficient.
Results: The results showed that MDI index had more correlation with environmental parameters dry bulb temperature (r=0.918, p<0.001) and relative humidity (r=0.43, p<0.001), also very high correlation coefficient with wet-bulb temperature and black-globe temperature (r>0.88, p<0.001). Among the thermal indices used in this study, MDI index had more correlation coefficient with three other indices. On the other hand; MDI had the highest correlation coefficient with oral temperature (r=0.508, p<0.001) and the higher correlation with the tympanic and skin temperature after the WBGT index. In all cases, there was a very good correlation between MDI and other indicators at different times of day.
Conclusion: It can be concluded that MDI, despite being simple, lack of need for sophisticated equipment to measure, having a high correlation with physiological parameters, low cost and easy interpretation can be used as substitute for the WBGT index in the range of temperature and humidity study.
 
Keywords: Heat stress, Direct indices, Modified discomfort index, Physiological parameters, Open-pit mines.

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Background and aims: Nowadays, global warming and climate change have become one of the controversial topics that have an impact on the health of individuals and the threat to human life. In recent decades, particular attention has been paid to the issue of environmental change and its impact from different perspectives. Many studies have been conducted to study these effects (generally from a non-occupational perspective) around the world. But from a job standpoint, the probable effects of global warming on occupational health are under reached, although its trend is growing. Outdoor workers are one of the most vulnerable groups of people directly affected by global warming. Climate change and global warming can cause many health problems, one of the most important of which is the development of thermal stresses and related disorders in outdoor occupational exposures.  Iran is a large country with very wide climatic diversity, with 35. 5% of it in complete arid, 29.2% of the arid, 20.1% of the semi- arid, 5% of the Mediterranean and 10% of the Wet climates in the country. Thus, more than 82% of the territory of the country is located in the arid and semi-arid region of the world. The average rainfall is 250 mm, less than one third world-wide (860 mm), and its dispersion degree is very high in the country. Increasing the average temperature can lead to warmer days and longer and more frequent heat waves. This, in turn, can increase the risk of heat-related diseases such as heat stroke, heat cramp, heat exhaustion, etc., and even in advanced cases, causes death. These effects are likely to be different in different regions, based on the sensitivity of the community, the amount and duration of exposure, as well as the ability of individuals to adapt to temperature variations. So, the main objective of this study was to investigate temperature changes in different climates of Iran in the coming decades in order to obtain an adequate understanding of the heat stress state in outdoor environments.

Methods: The environmental parameters required in this study were air temperature (ta), wet temperature (tw) and relative humidity (RH) which are determined by calibrated devices. At the same time, the WBGT temperature index was also measured and recorded using the calibrated WBGT meter, Casella model. All measurements were carried out at three times throughout the day, including 9 am, 12 noon and 3 pm, indicating the initial, mid, and final hours of shift work in the studied environments in the country, respectively. In order to cover this study throughout the country, and taking into account all the existing climates in the country, with the exception of areas with cold- dry and cold- humid climates, which often include the western and northwest parts of the country, 9 climatic zones in each country were selected in that country. A total of 495 measurement series of environmental parameters were carried out in nine climates (55 measurements per each climate). All measurements were done in outdoor settings such as open pit mines, asphalt and road workers, farmers, cement factories and shipbuilding industries. The selection of industries and locations was also performed randomly. Selected sites in this study, each representing different climates in the country, included cities of Ahwaz, Bandar Abbas, Rasht, Gorgan, Kerman, Yazd, Sari, Qom and Mashhad.

The Arc / GIS 8.0 software was used to generalize the data from a meteorological station to other weather stations in a similar climatic zone, and the environmental parameter values ​​measured at each station were similar to the other meteorological stations in the same climate were linked. Thus, in the GIS information layers, different climate zones were determined using two parameters of air temperature and humidity. In this process, the gathered spot data was converted into regional data. In addition, the long-term data for each climate zone (between 1965 and 2010), including the minimum and maximum daily air temperature, rainfall and sunshine, were used to generalize the data to other similar climate zones. Finally, using the weather behavior of previous periods at the studied stations, the weather conditions between 2011 and 2100 using the LARS-WG model and a coupled atmosphere-ocean general circulation model (HadCM3) for each of the 9 weather stations, simulations were performed. Then, according to the goal of the study that emphasizes the stress on outdoor work space, this model evaluates climate change in different regions based on daily maximum and minimum temperatures up to 2100 at 25-year intervals.

 

Results: Based on the results, a temperature increase with different intensities is expected in the next decade. In addition, the pattern of variations was almost the same for all stations studied. On the other hand, slight changes in the average daily minimum and maximum air temperature are observed until 2025. These changes were not very different in the spring and summer. After that, by 2075, the temperature increase is observed with a gentle slope, and thereafter, until 2100, no significant changes are observed for most of the stations. However, there is a significant increase in the average daily minimum and maximum temperatures in summer compared to spring. According to the results of the model, the highest temperature rise in 2075 is expected in most parts of the country. 

In general, the mean and standard deviation (M ± SD) of expected changes at minimum and maximum temperatures were 1.34 ± 1.41 °C and 1.29 ± 1.40 °C for spring and 2.38 ± 2.44 °C and 2.34± 2.48 °C for the summer, respectively. The respective values, regardless of the season (spring or summer) were1.86 ± 2.05 °C and 1.82 ± 2.07 °C for the minimum and maximum temperature changes, respectively. In general, it can be said that the average temperature of different climates of Iran will increase by about 2 °C until 2100. 

The results of the thermal stresses in the nine areas studied, which were simultaneously with other environmental parameters of the study, showed that in the spring, except for climatic zones 5 and 6, which are related to the cities of Yazd and Bandar Abbas, at least at 12 noon, no significant stress was observed in any of the affected areas. However, over time and approaching the afternoon (until around 3:00 pm), many other climatic zones, including sites 2, 7 and 8 (cities such as Ahvaz, Sari and Gorgan) , In addition to sites 5 and 6, will be in a stressed state even in the afternoon. 

In other words, in almost all parts of the country, especially in the middle and end of shift work, there is heat stress in the summer or even in many areas in the spring. The lowest WBGT index was 17.5 ± 0.99 °C for the early hours of the morning (in the spring and in the northern regions of the country) and the maximum is 35.10 ± 0.55 °C for noon and evening hours (in the summer and in the southern regions of the country). In general, the analysis of temperature differences and heat stress in different parts of the country also shows that parts of the country that have the greatest impact on climate change are the central and southern regions of the country. 

These findings clearly show that many workers, especially those working in outdoor environments, are currently in an environmentally unfavorable condition (regardless of any possible increase in temperature as a result of climate change) and they suffer from the dangers and complications of thermal stress.

Considering the objectives of the study as well as the obtaining results about climate change during the current century (about 2 °C), it can be expected that the trend of changes in thermal stress in the country will also change in most parts of the country similar to the trend of temperature changes in the country in the coming decades.

Conclusion: Climate change caused by global warming and, as a result, increased heat stress, especially for outdoor workers, is a very important issue that has relatively similar effects in different parts of the world. Based on the obtained results, an increase of about 2 degrees Celsius to the average temperature of the air, regardless of the changes in other parameters affecting heat stress such as relative humidity, air velocity and radiant temperature, can put several parts of the country under thermal stress conditions. In other words, the different areas and external environments that are currently in terms of acceptable thermal stress status will suffer from heat stress due to climate change and rising temperatures in the coming decades. For example, it is expected that the northwest, west, and northern and central parts of the country will be exposed to heat stress. 

In addition, most of the southern and central parts of the country, which are currently in heat stress, will be in a worse situation. Therefore, preventive interventions such as open outdoor environments design, shading in industrial areas, designing cool rest areas to reduce exposure to heat, developing work and rest programs, attention to acclimatization to the environment and observing public health programs, can play an important role in reducing the adverse health effects of climate change and the increase in temperature on exposed outdoor workers.

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Background and aims: Musculoskeletal disorders related to work are one of the most common causes of absenteeism. In order to reduce the damage caused by these disorders, first, we should try to identify the risk factors and the factors affecting it, and in the next step, evaluate them. The purpose of this article is a systematic review of the methods of risk assessment of ergonomic factors related to musculoskeletal disorders.
Methods: In this review, all articles published in Farsi and English in the field of ergonomic risk factor evaluation methods related to musculoskeletal disorders (March 2015 to December 2022) (last search date) were investigated. For this purpose, a systematic search of articles using Persian keywords (methodology, hand carrying loads, observational methods, instrumental methods, self-report methods, physical condition, questionnaire, musculoskeletal disorders, upper limb, lower limb, evaluation risk, ergonomic assessment, posture assessment) and their English equivalents were performed in PubMed, Google Scholar, Web of science, Cochrane library, Embase, SID, Scopus, Magiran Iran Medex databases. Unrelated articles were removed using PRISMA statement guidelines, and finally articles that were completely related to the study were examined. GraySource and BASE databases were used to find gray sources.
Results: Initially, 1176 articles were identified from different databases and a total of 82 articles were selected for final review. In some reliable sources, the risk assessment methods of ergonomic factors related to musculoskeletal disorders are classified into three categories: observational (42 articles), instrumental (11 articles) and self-report (29 articles). Pen-paper-based observational methods were among the most common methods used in ergonomic evaluations. Among the investigated individual reporting methods, the Nordic questionnaire was the most widely used tool (87% of the articles), followed by the Cornell questionnaire (13% of the articles). Some occupations, such as nurses, also have specific methods for assessing ergonomic risk factors (MAPO, DINO).
Conclusion: It is suggested that the ergonomic risk assessment methods of musculoskeletal disorders should be multi-factorial (individual, occupational and psycho-social) and specific methods should be developed for jobs with high diversity in job duties.

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Background and aims: Work-related musculoskeletal disorder is a multifactorial complication that leads to a loss of work time, inability, and increased economic cost. The aim of this study was to identify the factors affecting the musculoskeletal disorders of tea harvesting workers.
Method: The current descriptive-qualitative research was conducted with directed content analysis where in 14 participating tea pluckers were selected through purposive and snowball sampling methods. Data were collected by semi-structured interview method and were then analyzed in MAXQDA12 software. In this study, Carayon’s SEIPS model was used as a predetermined framework for the macroergonomics approach.
Results: The numbers of 214 primary codes, 56 important codes, 17 subcategories, and 5 main categories (i.e., individual, task-related, tools and technologies, environment-related factors and organizational) were obtained as the effective factors in musculoskeletal disorders among tea harvesting workers in the results of continuous analysis. Important codes extracted from the interview in the individual category including (age, gender, previous work experience in tea plucking, feeling very tired, etc.), task-related category (improper posture, exerting force on trunk and hand, etc.), the category of tools and equipment (the long length of the bag attached to the hand tool for picking tea, etc.), the category related to environmental factors (surfaces uphill and downhill), the height of the tea plant (short and tall), the type of tea harvesting area (plains and mountains, etc.) and organizational category (lack of sufficient training on the correct way of doing work, lack of support and support from the employer and threat of dismissal (lack of job security) and...).
Conclusion: Considering that agricultural jobs (especially tea harvesting) have diversity in the nature of tasks compared to industrial tasks, among the different factors on musculoskeletal disorders in this job, it can be attributed to the greater activity of women in this job due to the need for High physical activity, manual handling of tea bags (60 to 80 kg), using traditional hand tools, humidity and temperature of the working environment (working outdoors in the summer season and under rain), working environment (height of the tea plant, limited access to all tea plant space), the uneven surface of the ground during activity, applying force on the hand (crossing movements of hand tools while working), not establishing a shift work system and working hours over 12 hours. In order to prevent these disorders, a multi-faceted approach of actions from these factors is needed, which can be ergonomic redesign of tea growers' work tools, improvement of tea plants and work space, training of ergonomic principles of body posture and load handling, creating insurance coverage and Other related cases were mentioned in this study.