پديد آورندگان :
رشيدي، محمد امين دانشگاه تربيت مدرس - دانشكده علوم پزشكي - گروه مهندسي بهداشت حرفه اي، تهران، ايران , حاجي زاده، روح اله دانشگاه علوم پزشكي زنجان - دانشكده پيراپزشكي و بهداشت - گروه مهندسي بهداشت حرفه اي، زنجان، ايران , بهشتي، محمد حسين دانشگاه علوم پزشكي گناباد - دانشكده بهداشت -گروه بهداشت حرفه اي، گناباد، ايران , اكبري، عظيم دانشگاه تربيت مدرس - دانشكده علوم پزشكي - گروه مهندسي بهداشت حرفه اي، تهران، ايران , پورنجف، عبدالحسين دانشگاه علوم پزشكي ايلام - دانشكده بهداشت - گروه مهندسي بهداشت حرفه اي، ايلام، ايران , خوانين، علي دانشگاه تربيت مدرس - دانشكده علوم پزشكي - گروه مهندسي بهداشت حرفه اي، تهران، ايران , پورنجف، مسعود نيروگاه سيكل تركيبي نوشهر، مازندران، ايران , نيكوند، فرشته مركز بهداشت شهرستان ايلام، ايلام، ايران , فقيه نيا ترشيزي، يوسف دانشگاه علوم پزشكي ايران - مركز تحقيقات بهداشت كار، تهران، ايران
چكيده لاتين :
Background and aims: Inappropriate atmospheric conditions are harmful factors that
cause particular problems in certain seasons (summer or winter). The occupation of
confectionery in the regions like Ilam causes severe problems due to the heat generated
by the nature of the work (synthetic heat-generating processes) and the heat resulting
from the climatic conditions in the region. Exposure to excessive heat, in addition to
disrupting the physiology and health of the individuals that may cause many diseases
and complications, also affects their efficiency and safety. One of the indices of heat
stress is the WBGT index, confirmed by various national and international
organizations and institutions as the standard method for measuring heat stress. WBGT
index engages important environmental factors directly or indirectly in its
computational structure. The Discomfort Index (DI) has been recommended for more
than four decades along with the WBGT index for the evaluation of warm
environments. Today, the oral temperature is used to determine the heat stress and
strain. In addition, oral temperature is one of the important parameters for the validation
of indices. Therefore, in order to prevent the occurrence of heat stress complications in
occupational environments, a study was conducted to determine the amount of heat
stress in the employees of confectionery workshops in Ilam city, so as to identify the
factors affecting the heat stress of workers and to provide recommendations for the
reduction of these risk factors and to create a healthy working environment.
Methods: This descriptive-analytical study was carried out on 104 workers in 35
confectionary workshops in summer of 2017. The sample size was selected based on
census method. Prior to the study, the workers were monitored through medical records
and interviews, and, two of them did not qualify for inclusion in the study.
Measurement of the study variables was performed at the hottest work hours (10 to 14),
once for each worker, in the worst workstation (nearest to the heat source). In the
present study, four groups of occupations, i.e. workers of oven, mixer, flattener,
cleaning and packaging, three types of ovens, i.e. layered, winch and furnace, and three
productions of wet and dry pastry, cake and French bread, Baghlava and Ka’ak.
Assessment of heat stress was performed by the WBGT (based on ISO7243 standard)
and the DI indices. Metabolism and activity of workers were calculated according to the
ACGIH standard. Also, the working pattern was 75% of the work-25% of the rest, and
according to ISO 9920, the clothing insulation coefficient in WBGT calculations was 0.6 clo. Along with the environmental parameters such as dry bulb temperature, natural
wet bulb temperature, globe bulb temperature, relative humidity and dew point
temperature, the oral temperature of the workers was measured by a digital medical
thermometer. Finally, data analysis was performed using SPSS v.22 and statistical tests
of Kolmogorov-Smirnov, Mann-Whitney, Kruskal-Wallis, one-way ANOVA and
Pearson correlation were performed.
Results: Findings of this study showed that the mean of WBGT index in the workers of
oven, mixer, flattener, cleaning and packaging was 33.66±3.96, 29.58±3.05, 31.73±3.61
and 29.87±2.4. Also, this index was 30.94±3.86, 34.14±3.89, and 32.2±2.91 for the
winch (wet and dry pastry), layered (cake and French bread), and furnace (Baghlava and
Ka’ak) ovens (products). These results show that the amount of heat stress in working
with the oven and the cake and French bread product (layered oven) was more than
others. Kruskal Wallis tests and one way ANOVA showed a significant difference
between the mean of WBGT and DI indices with job variables, type of oven and
products (p <0.05). A 95% confidence interval was observed in terms of the WBGT
index between the subgroups of the oven and flattener, oven and cleaning and packing,
layered oven and winch oven, and French bread and the wet and dry pastry. However,
in terms of the DI index, this difference was found between the sub-groups of the oven
and cleaning and packing, oven and mixer with flattener, layered oven and winch oven,
and French bread and the wet and dry pastry. Pearson correlation test showed that there
was no significant correlation between oral temperature and indices and variables
(p<0.05). Based on the results of this study, the mean of WBGT index at the heights of
head, waist and ankle was 32.54±5.01, 31.54±3.86 and 30.49±3.12, respectively. Also,
according to Kruskal Wallis statistical tests and one way ANOVA, there was a
significant difference in WBGT index and dry bulb temperature, natural wet bulb
temperature, globe bulb temperature and relative humidity at the heights of head, waist
and ankle (P <0.05). The results of the Mann-Whitney test indicated that there was a
significant difference between the gender variable and the oral temperature (p <0.05),
with the mean of this variable was higher in women (36.7±0.27) than men (36.42±0.84).
The results of this study showed that 85.6% of the subjects had a “severe” discomfort
index (DI), and regarding the WBGT index, 14.4% and 85.6% were lower and higher
than the threshold, respectively.
Conclusion: According to the results, almost all of the workers in the confectionary
workshops are exposed to heat stress, but subgroups of oven, mixer, layered oven (cake
and French bread), furnace oven (Baghlava and Ka’ak) and the females were exposed to
higher stress. So, these subjects have a priority when adopting control measures. It is
recommended that measures such as pre-employment examinations, preparation of
proper drinks, training the workers, reduction of working time, using thermal shields,
using air conditioning system, and paying particular attention to reducing the wet
temperature and relative humidity of the workplace are taken to minimize the exposure
to heat and the resulting diseases.
