|Year : 2015 | Volume
| Issue : 3 | Page : 156-162
Investigating the occupational accident rate in Mines and Industries due to change in official time in Iran, a month before and after the spring and summer changes
Beheshteh Jebelli1, Elham Ghazanchaei2, Gholamreza Nabi Bidhendi3, Hassan Hoveidi3, Mohamad Javad Amiri3
1 Clinical Tuberculosis and Epidemiology Research Center, Tehran, Iran
2 Lung Transplantation Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran; Research Institute of ShakhesPajouh, Isfahan, Iran
3 Faculty of Environment University of Tehran, Tehran, Iran
|Date of Web Publication||20-May-2015|
Research Institute of Shakhes Pajouh, Isfahan
Source of Support: None, Conflict of Interest: None
Introduction: A quarter of the world's population experience one-hour change of time twice a year (due to daylight saving time or DST). Disruptions in the circadian rhythm may have harmful impacts on health. Circadian rhythm disruptions caused by changed biological clock lead to a change in sleep quality and length, which might result in accidents due to fatigue, headache, and loss of care and consciousness. Through transitions into and out of DST plan, the environmental and social clock change biannually. According to the review of literature, transition into and out of DST plan disrupts balance in circadian rhythm and may lead to sleep disruptions. Therefore, the aim of this study is to explore the effect of DST plan on the occupational accidents experienced by the workers in Mines and Mining Industries Development and Renovation of Organization in the months before and after DST transition. Materials and Methods: In this survey, using the databank of Iran's Organization for Development and Renovation of Mines and Mining Industries, we analyzed all occupational accidents during 9 years, from 2003 to 2011 in the months before (21 st February-20 th March and 23 rd August-22 nd September) and after DST (21 st March-21 st April and 23 rd September-23 rd October). Moreover, the year 2006 in which DST was not implemented in Iran was compared with other years. Results: The results yielded through statistical tests suggested that the number of occupational accidents had no significant increase in the months before and after DST during these 9 years, and there was no significant difference between 2006, when DST did not occur in Iran, and other years (P > 0.05). Conclusion: The study findings reveal that DST experienced by the workers at industrial factories, the risk of accidents and that of occurrence of severe occupational accidents do not significantly increase.
Keywords: Circadian rhythm (body biological clock), day light saving time, occupational accidents
|How to cite this article:|
Jebelli B, Ghazanchaei E, Bidhendi GN, Hoveidi H, Amiri MJ. Investigating the occupational accident rate in Mines and Industries due to change in official time in Iran, a month before and after the spring and summer changes. Int J Health Syst Disaster Manage 2015;3:156-62
|How to cite this URL:|
Jebelli B, Ghazanchaei E, Bidhendi GN, Hoveidi H, Amiri MJ. Investigating the occupational accident rate in Mines and Industries due to change in official time in Iran, a month before and after the spring and summer changes. Int J Health Syst Disaster Manage [serial online] 2015 [cited 2021 Mar 2];3:156-62. Available from: https://www.ijhsdm.org/text.asp?2015/3/3/156/157389
1 The first day of Farvardin in Iranian Calendar (Solar Hijri calendar)
2 The first day of Mehr in Iranian Calendar (Solar Hijri calendar)
3 Months before change time (21st February-20 March and 23rd August-22 September)
4 Months after change time (21st March-21st April and 23rd September-23rd October)
| Introduction|| |
A quarter of the world's population is subjected to a one-hour time change twice a year due to daylight saving time (DST). 
In Iran, DST or advancing the official clock by one hour in spring (21 st March) and back again in autumn (23 rd September) has been observed as a rule for several years in order to coordinate people's activities to daylight time.
The idea of DST was first conceived by Benjamin Franklin in 1784 during his stay in Paris. He published an essay entitled "An Economic Project for Elimination of the Cost of Light" in which he proposed to economize the use of candles by rising earlier to make use of morning sunlight. 
Changing the official time as the plan of DST is now observed in over 70 countries worldwide. Although many countries observe DST, the start and the end time of DST often differ in different countries. 
Economically, DST could have good effects, but it has also caused some worries in terms of increasing the incidence of accidents.
Researches indicated that time change due to DST leads to mild symptoms of jetlag such as sleep disorders, disrupted circadian rhythm, fatigue and increased occupational accidents; and different studies have been carried out on the health problems caused by circadian rhythm disruption. Insomnia, jetlag, work shift and DST may disrupt circadian rhythm. Circadian rhythm disruption leads to insomnia and mood, which might increase the incidence of accidents and psychological disorders. Since circadian rhythm is an endogenous rhythm, it does not adapt rapidly with a sudden change in the light-dark cycle. ,,
Yearly, DST affects millions of people and disrupts circadian rhythm, but its effects on different aspects of human's life are partially unknown. One of the most important aspects is safety.
It has been demonstrated that DST causes disruption in sleep-wake cycle and may therefore influence cognitive functions such as concentration, memory and mood. Since, sleep deprivation and circadian rhythm disorders reduce consciousness and concentration, changing time due to DST might increase the accident risks. Few studies have been conducted in this area and the results are not very consistent. Thus, theoretically it is likely to increase the incidence of accidents due to DST. Most of the studies carried out in this area are about traffic accidents. ,,
Researches have shown a remarkable increase in the number of traffic accidents during the spring DST transition due to loss of one-hour sleep. Sleep deprivation leads to a slight increase in number of fatal crashes on Monday, directly following the spring switch to DST, but only inconsistent results have been obtained about the relationship between traffic accidents and DST. Studies have also shown that DST in a full year decreases annual pedestrian fatalities by up to 171 persons or 13% of the total pedestrian fatalities between 5 and 10 a.m. and between 4 and 9 p.m. Moreover, passenger fatalities decrease up to 195 people annually or 3% during the same period. ,, Given the conflicting results in this regard, some studies have shown that a number of accidents increased due to DST while some others have proposed reduced accidents due to DST. It is shown in relevant articles.
Data suggests that even relatively low sleep deprivation and sleep-wake cycle disorders might increase the risk of heart failures or myocardial infarction among the population. 
Occupational accidents are highly costly in modern societies. The European Agency for Safety and Health at Work (EU-OSHA) has estimated that 4.6 million occupational accidents occur in the European Union (EU) annually, which means that the EU loses almost 2.6 to 3.8% of the gross national product. Therefore, on the one hand work-related accidents impact workers and their families, while on the other hand it wastes the capital and enfeebles the economic foundation of the society. Such accidents are therefore important individually, socially and economically. 
Hence, it is also important economically for the society to attempt to prevent occupational accidents. Since in Iran, no researches have been conducted in this area and DST was not implemented once in 2006, there is a good chance to compare the impact of DST on occupational accidents in different industries. Thus, researchers decided to carry out the present study.
Given that sleep disorders due to changes in circadian rhythm can lead to increased risk of accidents, and the change is most effective within 15 days to a month, it has been studied only 30 days before and after the official time (DST) was changed. We also considered the time of the accident from the time that the work begins. Furthermore, we considered the occupational accidents due to human errors, and eliminated the rest of the occupational accidents due to non-human errors.
| Materials and Methods|| |
This study investigated the accidents occurred during a 9-year period in Iranian Mines and Mining Industries Development and Renovation Organization (IMIDRO).
This organization was founded in order to survey, prepare and undertake construction, development, equipment and renovation projects in metallurgy production industries, mining and exploitation of minerals, as well as operating discovery plans. It comprises 51 subsidiaries company; moreover, it controls an Iranian Institute for Mineral Exploiting Research. The foregoing organization has four major departments: 1. Mining, 2. Steel, 3. Aluminium, and 4. Copper, and each one has multiple subsidiaries. Total number of the workers at this organization has ranged between almost 81,870 and 119,680 during 9 years from 2003 to 2011. The statistical population comprises all members of workers serving with the subdivisions of IMIDRO from 2003 to 2011. First, we prepared a checklist containing the intended information through reviewing the previous literatures. This checklist comprises personal traits, information about occupational accidents such as time, place, type, severity, type of industry, employment history, educational background, and so on. The study investigated the accidents occurred to the workers at the industries under the supervision of this organization in the months before and after change of time during the 9 years from 2003 to 2011. Research sample comprises all accidents from 2003 to 2011, which is reported to be about 10,000 cases. To collect the data, firstly the percent of the accidents in the above-noted months was investigated using the prepared checklist and the databank of IMIDRO. Then, the relation between the factors, including severity of accidents, workers age, educational background, work shift, type of accident, type of industry and employment history was investigated a month before DST (21 st February to 20 th March and 23 rd August to 22 nd September) and a month after DST (21 st March to 21 st April and 23 rd September to 23 rd October). Finally, the case of 2006 in which the time did not change was compared with other years. The data were analyzed statistically using the SPSS 16 software. In this study, all occupational accidents in the months before and after the official time were evaluated based on the database of this organization. All incidents were examined in the months of April and March, and September and October and the data were analyzed using the statistical method SPSS 16.
In this study, the data obtained from 2,891 accidents in 4 industries, including aluminium manufacture, steel manufacture, Iranian Mineral Production Co., and Iranian National Copper Industries Co. in months before change of time and after change of time were investigated. The severity of accidents was classified into two categories: severe accidents and mild accidents. Severe accidents included death, amputation, electric shock injuries, laceration and internal organ damage, fracture and dislocation, while mild accidents included cuts and wounds, burns, bruise, contusion, sprains, different types of poisoning, an external object entering into the eyes, lesions caused by straining, an external object entering the body, multiple injuries and so on.
| Results|| |
The average of the total numbers of workers in IMIDRO was 100,775 during the 9 years from 2003 to 2011. All workers were men. [Figure 1] shows the frequency distribution of the incidence of accidents occurring from 21 st February- 21 st April and from 23 rd August-23 rd October between 2003 and 2011. The total number of workers for each year is given in [Table 1].
|Figure 1: Frequency Distribution of the incidence of Accidents from 21st February- 21st April and from 23rd August-23rd October between 2003 and 2011|
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As it is shown in [Figure 1], the most number of accidents occurred in October (772 accidents), while the least number of accidents occurred in April (656 accidents). The number of accidents from 2003 to 2011 in the months before and after DST is given in [Table 2].
|Table 2: Frequency distribution of events in different months from 2003 to 2011|
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As shown in [Figure 2], accidents decreased significantly during the 9 years (P < 0.001). The total number of accidents from 2003 to 2011 is given in [Table 3].
Frequency distribution of the education level of injured workers before and after DST indicated that most accidents occurred to those with high school diplomas (1,142 cases), middle school (853 cases) and primary school (530 cases), respectively. The distribution frequency of the education level of injured workers, before and after DST is provided in [Table 4].
|Table 4: Frequency Distribution of the Education Level of Injured Workers before and after DST|
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Investigating the accidents etiologically demonstrated that the most common cause was unsafe acts (1,712 cases).
Moreover, frequency distribution of the type of accidents suggested that the most common types of accidents in the months before DST transition were collision, strike, accidents (380 cases), and being struck by an abandoned object (273 cases). The most common types of accidents in the months after DST transition were collision, strike, accidents (392 cases) and falling from higher to lower surface (256 cases).
The frequency distribution of work shift before and after DST transition revealed that most of the accidents occurred in the morning shift (1,370 cases).
The results showed that in all shifts, the maximum number of accidents took place in the months before DST transition in the fourth hour after starting the work shift (283 cases) and in the months after DST transition in the third hour (255 cases). Furthermore, the most number of accidents in the months before DST occurred for the age range of 20-39 (1,113 cases) and also in the months after DST transition occurred for the same age range (1,091 cases).
The most common location of injury in the months before and after DST execution happened in lower extremity (980 cases) and upper extremity (961 cases), respectively.
The results suggested that the most frequency of accidents in both, before and after DST transition during these years related to the workers with less than 5 years of employment history (1,447 cases).
The frequency distribution of accident occurrence in different days of each month indicated that when comparing months before and after the spring change (from 21 st February- 21 st April), the accidents mostly happened in early April and late February (P < 0.05), and when comparing between months before and after the autumn change (23 rd August-23 rd October), the accidents mostly took place on 23 rd August and late September (P < 0.05).
Given that the events were divided into mild and severe groups, each event has been divided based on a contract into two groups. The severe events were death, amputation, electrocution, lacerations and internal organ injuries, fracture and dislocation, while the mild events were cuts and wounds, burns, strains, bruises, sprains, different types of poisoning, entering of external object into the eyes, injuries caused by straining, entering of external object into the body, multiple injuries and others. According to this, the total percentage of mild and severe accidents is presented in [Table 5].
|Table 5: Investigating the relation between accident severity and case study variables|
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Likewise, when it comes to the relation between severity of accidents and time of accident occurrence, education level, DST, type of industry, age, employment history and work shift, the results are displayed in [Table 5].
The results also suggested that in 2006 when DST was not implemented, the accident rate was not significantly different from other years (P > 0.05).
[Figure 3] shows the comparison between the accidents occurring in the months after DST (21 st March-21 st April and 23 rd September-23 rd October) and before DST (21 st February to 20 th March and 23 rd August to 22 nd September). The results indicate no significant difference (P > 0.05).
We used logistic regression test in order to examine more precisely the impact of the research confounding factors on the relation between DST and severity of accidents, and the results are displayed in [Table 6].
|Table 6: Investigating the impact of research confounding factors on the severity of accidents using logistic regression test|
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The results showed that age had a significant role on the severity of accidents (P < 0.05), while other factors including DST were not related significantly to the severity of accidents (P > 0.05).
| Discussion|| |
In this study, totally 2,891 cases of occupational accident in months during the studied period (from 21 st February- 21 st April and from 23 rd August-23 rd October), i. e., before and after DST transition during the 9 years from 2003 to 2011 were recorded in IMIDRO.
According to the obtained results from the study, the age of injured workers at this organization from 2003 to 2011 ranged between 20 and 60. This is almost similar to the result of the study carried out on the production line workers of Pars Khodro Co. (Car Manufacturing Plant In Iran) in 2008, in which the average age of the injured people was 29.80 ± 5.9 (ranging from 16 to 60). 
The findings indicated that the accident rate was higher in October, but according to the frequency distribution of the accidents in the months before and after DST in these 9 years, the results showed that there is no significant difference in the frequency of accidents in the months before and after DST (P > 0.05). Lahti et al., also carried out a study on occupational accidents and DST project in Finland in which they analyzed all occupational accidents occurring in Finland one week before and after DST transition from 2002 to 2006. The results of the study indicated that transitions into and out of DST showed no significant and considerable increase in the number of occupational accidents.  This result matches our study.
Another study carried out by Morrassaei et al., in Ontario, Canada, in 2010 in which data concerning with work-related accidents from 1993 to 2007 were collected from the dossiers of claim for compensation received from insurance board and workplace safety. The results of the foregoing study indicated no increase in the occupational accidents in early days after starting DST transition.  This result also corresponds with our study.
Similarly, a study conducted by Christopher et al., in 2009 suggested that from 1983 to 2006, the workers had experienced more severe and more accidents at workplace on Monday directly following the spring switch to DST in which the rest time reduces by one hour in comparison to other days. In workers who had senior high school, junior high school and elementary school education, the study revealed that the lower the level of education the higher the level of experiencing accidents. Given the type of occupation, it is obvious that the higher the workers' educational background the lesser the level of occurrence of occupational accidents. Likewise, the results of the study showed that the most frequent cause of accidents in different industries in all the four months was unsafe acts. Similar studies have also demonstrated that carelessness is always among the major causes of occurrence of occupational accidents; for example, in two studies carried out in 2003 and 2006, carelessness was reported to be the main cause of accidents. ,
The results indicated that the most common occupational accidents happening during these 9 years before and after DST transition were collisions, strikes, accidence, being struck by abandoned objects and falling from higher to lower surface. In similar results achieved by Hamalainena et al., the most frequent type of accidents was falling. 
The results suggested that morning shift was the shift in which most accidents occurred before and after DST, because the main activity of workers is fulfilled in the morning shift.
The results indicated that the most frequent hours, in all shifts before and after DST are the third and fourth hours after start time of work, which can be considered to be caused by coincidence with coffee time and workers' fatigue.
Young workers with less than 5 years of employment history experienced the highest percent of accident among the workers in the organization studied; therefore, it seems that the frequency of the work-related accidents associated reversely with age and employment history. ,
Anatomically the most frequent injured location before and after DST is the lower and upper extremity that corresponds to the study carried out by Loomis et al. 
According to the obtained results, the most common types of injury experienced by the workers of IMIDRO, before and after DST include contusion, bruise and sprain. This result shows that contusion is the most frequent type of accident and it matches with other studies, including the one carried out by Loomis et al.
In the same way, Macedo et al., reported contusion as the most frequent type of occupational accident. 
There is some strength in this study: It has high reliability, since we examined a large sample that comprises several types of Mining and Industry using a comprehensive databank, and we worked on real workplace injuries. It is also highly powerful statistically; therefore, this is the first study in Iran. Since the database contains all information such as type of injury, cause of accident, age, employment history, type of industry, education level of injured people, injury location, severity of injury, the time of incident from the time that work starts, human and non-human errors, etc., the bank is considered as a master database.
| Conclusion|| |
Generally, the results of the study indicate that experiencing DST by the workers serving in industrial factories, the risk of accidents and the occurrence of severe occupational accidents do not increase significantly, and this plan may be applied without any concern about increasing the number of occupational accidents in the industrial factories. According to that there is no significant relationship between the increased occupational accidents and the change of official time; time change in spring and summer can be implemented without affecting the trend of occupational accidents. In order to reduce the accidents, considering other factors such as regular training of workers and managers, better monitoring of workers, repair and maintenance of machinery and equipment may have an effective role. Although the result of the study showed no effect of time changing on occupational accidents and no significant relationship between them, so in general, the researcher has some recommendations in order to reduce the risk of occupational accidents at this time and the implementation of them can be effective to reach the purpose.
Given that working conditions in different industries are varied, the results are related to steel, aluminium, copper and minerals industries. Different results are possible in other industries and therefore it cannot be generalized.
| Acknowledgement|| |
We especially appreciate Dr. Noori, the President of HSE in Iranian Mines and Mining Industries Development and Renovation Organization (IMIDRO), and Mr. Valadkhani, Master of Occupational Health, for all their cooperation during this study.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]