Abstract
Objective: This study aimed to assess the thermal comfort trend using a metrological parameter based on the Summer Simmer Index (SSI), for different climates of Iran between 1985 and 2014. Methods: This is a Time-series study. The new SSI was calculated using metrological data in a 30 year- period for illustrating the changes to the thermal comfort or discomfort level through summer months in different climates of Iran. Mann- Kendall test and Sen's Slope were used to compare the upward or downward trend of the index during this period. Results: The worst thermal condition was observed in the southern and central regions of the country. A few stations were put in comfort zone (77≤SSI<83°F). The fluctuations of SSI were not considerable during the study period (P<0.001). However, a commonly upward trend was observed, indicating rising temperature. This initial assessment, which can be reported daily along with other atmospheric parameters at meteorological stations, could play a significant role in reducing the heat-related complications among exposed individuals and a basis for taking appropriate protective measures. Conclusion: Based on the results obtained in this study, which has been investigated in Iran for a long period of time, considering intrinsic features of the SSI index, such as ease of calculation and interpretation and also the possibility of calculating the index using daily reported meteorological data, the use of SSI as a screening index of thermal stress in order to adopt preventive policies in outdoor settings in climates of Iran is recommended.
Highlights
The adverse effects of climatic conditions and global warming along with various job tasks requirements, such as wearing heavy or non-breathable protective clothing and equipment, prolonged exposure to the heat sources and lack of proper control measures, for the outdoor jobs and during the hot seasons of the year have contributed to the prevalence of excessive levels of heat stress among employees
Our findings suggest that Summer Simmer Index (SSI) can be applied as a thermal comfort index in evaluation of thermal conditions in different climates
In another study, it was revealed that the maximum thermal stress based on the Wet Bulb Globe Temperature (WBGT) index could be seen in the Centre and South of the country (Heidari, Golbabaei et al 2015)
Summary
The adverse effects of climatic conditions and global warming along with various job tasks requirements, such as wearing heavy or non-breathable protective clothing and equipment, prolonged exposure to the heat sources and lack of proper control measures, for the outdoor jobs and during the hot seasons of the year have contributed to the prevalence of excessive levels of heat stress among employees. According to the statistics of Iranian labor organization, it is estimated that nearly sixteen million employees work in two million job units, of whom 45% work in the service sector, 30% work in agricultural sector and 25% work in industrial sector. These people are exposed to various harmful agents due to their work activities and environment. It can be estimated that the number of outdoor workers is much higher than those of indoor jobs (about three times) These workers, who often spend long hours in the outdoor environments, might be affected by heat stress through both the natural (due to sunlight) and artificial heating processes. The deterioration or comfort of working conditions and the relationship between workers' complaints and work performances led to the advent of bioclimatic comfort studies (Toy and Yilmaz 2010)
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