Journal of Environmental Treatment Techniques  
2021, Volume 9, Issue 1, Pages: 253-258  
J. Environ. Treat. Tech.  
ISSN: 2309-1185  
Journal web link: http://www.jett.dormaj.com  
https://doi.org/10.47277/JETT/9(1)258  
Prevalence of Heat-Related Illnesses among  
Outdoor Workplaces Workers in Hot and Dry  
Areas of Iran  
1
2
3
Milad Derakhshanjazari , Ali Jangjou , Roohollah Bagherzadeh , Mohammad Reza  
4
5*  
Monazzam , Zahra Zamanian  
1
Department of Occupational Health Engineering, School of Health, Shiraz University of Medical Sciences, Shiraz, Iran  
2
Emergency Medicine Department, Shiraz University of Medical Sciences, Shiraz, Iran  
3
Department of Textile Engineering, Advanced Textile Materials and Technology Research Institute (ATMT), Amirkabir University  
of Technology, Tehran, Iran  
4
Department of Occupational Health Engineering, Tehran University of Medical Sciences, Tehran, Iran  
5
Department of Occupational Health Engineering, School of Health, Shiraz University of Medical Sciences, Shiraz, Iran  
Abstract  
The risk of heat-related illnesses (HRI) is very high in outdoor workers. Given that there are a large number of outdoor workers in  
areas of Iran and there is no comprehensive information on HRI among these workers in the risky workplace. Aim of the study is  
prevalence of HRI among outdoor workplaces workers in hot and dry areas of Iran. This cross-sectional study carried out among 1800  
that randomly selected from outdoor workplaces workers in hot and dry cities of Iran in 2019. Data was collected by researcher-made  
questionnaire containing questions about information about the participants’ demography and lifestyle; behavior modification during  
heat; knowledge about HRI; health status of the workplace; type of HRI symptoms in the Sumer 2019; job properties; and individual  
factors. Then, data analysis was performed using SPSS software version 19. 76.2 % of the participants reported experiencing one or  
more HRI symptoms that 36% of them were related to headache. HRI is highest prevalence in agricultural workers (37%). HRI symptom  
are significantly associated with age, work experience, type of working clothes, and ratio of rest/work (p<0.001). Results showed that  
reducing rest time and water consumption increased the prevalence of HRI (p<0.001). Prevalence of HRI is very high in among outdoor  
workplace workers in hot and dry areas of Iran, especially agriculture workers. Headache is most prevalence in the workers. Finally,  
consideration of working clothes, water consumption, and ratio of rest/work have an important role in reducing of HRI.  
Keywords: Heat-related illnesses, Outdoor, Workers, Hot and dry  
1
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995 to 2005 (15). In Japan, 389 deaths occurred from 1989-  
012 due to heat shocks (16). The reports indicate the  
1
Introduction  
Heat stress as a physical agent or hazard is influenced by  
importance of heat stress in the workplace.  
environmental and individual factors (ie, air temperature,  
humidity, air movement, thermal radiation), the metabolic heat  
generated by human activity, and clothing type (1, 2). This  
adverse agent has many effects at outdoor and indoor  
workplaces such as agriculture, construction workers, ranchers,  
bakeries, glass industrials, smelters (3, 4). Excessive exposure  
to heat can cause physiological (5), and psychological effects  
Iran lies in western Asia. The population now estimated at  
0.0 million. The area coverage of different types of climate in  
8
Iran is 35.5 % hyper-arid, 29.2 % arid, 20.1 % semi-arid, 5 %  
Mediterranean and 10 % wet. Thus more than 82 percent of  
Iran’s territory is located in the arid and semi-arid zone of the  
world (17). There are 14 million workers in Iran, about 8.5  
million of whom work in outdoor workplaces. 30% of these  
workers work in 9 cities of Iran including Isfahan, Kerman,  
Sabzevar, Zahedan, Semnan, Kashan, Yazd, Zabol and Dezful  
that these cities are located hot and dry areas of Iran (18, 19).  
According to meteorological reports, the average dry air  
temperature and relative humidity over a period of 40 years in  
summer are about 30.2 Celsius degrees and 24 percent,  
respectively. Also, the radiation temperature in these areas is  
about 40 Celsius degrees (20). Given that there are a large  
number of outdoor workers in these areas of Iran and there is  
no comprehensive information on HRI among these workers in  
the risky workplace. Aim of the study is prevalence of heat-  
related illnesses among outdoor workplaces workers in hot and  
dry areas of Iran.  
(
6), heat-related illnesses (HRI) symptoms such as heat  
exhaustion, heat stroke, headache, vertigo, and vomiting (7),  
kidney disease, syncope (8), and heart disorder (9), and can also  
increase occupational accident risk (10). Heat-related illness in  
outdoor workers are higher than indoor workers, because of  
both environmental and occupational exposure to heat (11, 12).  
In addition, global average dry temperature has been  
increasing, the forecast for a rise of 1.8 to 4 degree Celsius by  
2
100 (13), For outdoor workers, sun radiations and climatic  
conditions (e.g. low air movement, low humidity levels and  
high dry temperature) can cause heat stress. Numerous studies  
have reported the prevalence of HRI in outdoor workplaces  
workers. In Australia, reports showed that there were 485 cases  
of HRI in the 11 years from 1997 to 2007 (14). Also, 480 cases  
of heatstroke occurred in the United States in the 11 years from  
Corresponding author: Zahra Zamanian, Department of Occupational Health Engineering, School of Health, Shiraz University of  
Medical Sciences, Shiraz, Iran. Koy-e-Zahra Street, PO Box: 71645-11, E-mail: zzamamian@yahoo.com.  
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Journal of Environmental Treatment Techniques  
2021, Volume 9, Issue 1, Pages: 253-258  
mean and standard deviation for age, work experience, and  
body mass index was 40.8 ±20.9, 8.3 ±7.1, 25.2 ±7.5 and years,  
respectively. The mean and standard deviation for weekly  
working hours was 57±2.4 hours, and 76.2 % of the studied  
workers have experienced at least one of HRI.  
2
Method and materials  
This cross-sectional study carried out to investigate the  
prevalence of HRI among outdoor workplaces workers in hot  
and dry areas of Iran in Sumer 2019. Isfahan, Kerman,  
Sabzevar, Zahedan, Semnan, Kashan, Yazd, Zabol and Dezful  
are cities in Iran. Studied workers were selected equally from  
each of cities using a random number table.  
Table 1: Socio-demographic characteristics of selected  
workers (N=1800)  
Frequency  
2
1
.1 Participants  
Variables  
(%)  
800 male workers with at least one year of work experience in  
≤20  
225 (12.5)  
755 (41.9)  
406 (22.6)  
414 (23.0)  
1194 (66.3)  
609 (33.8)  
1156 (64.2)  
416 (23.1)  
228 (12.7)  
640 (35.6)  
457 (25.4)  
470 (26.1)  
233 (12.9)  
813 (45.2)  
987 (54.8)  
589 (32.7)  
1211 (67.3)  
1031 (57.3)  
769 (42.7)  
951 (52.8)  
849 (47.2)  
880 (48.9)  
312 (17.3)  
350 (19.4)  
258 (14.3)  
1449 (80.5)  
351 (19.5)  
outdoor workplaces workers participated from studied cities.  
Participates haven’t history of disease. 200 participants were  
selected from each city. Finally, 50 participants were selected  
from each of the four jobs including construction workers,  
agricultural workers, ranchers, workers in brick industries. In  
cases where the workers of a workplace refused to participate  
in the study or quitted their work during the data collection  
period, the workplace was excluded from the study and was  
replaced by another one.  
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4
6
1-40  
1-60  
0<  
Age (Years)  
Married  
Single  
Primary education  
Secondary education  
Associate degree  
1-4  
5-9  
10-14  
Yes  
No  
Yes  
No  
Seasonal  
Permanent  
Yes  
No  
Cotton  
Marital status  
Education level  
Work experience  
(Years)  
2
.2 Data collection tools and quality control  
Data was collected by researcher-made questionnaire  
15  
including information about the workers demography;  
behavior during heat stress; knowledge about heat-related  
illnesses; occupational safety and health status of the  
workplace; type of HRI; job properties; and individual factors.  
The validity of the questions was confirmed by 30 occupational  
health and safety experts. For this purpose, questionnaires were  
sent to experts by e-mail and they gave us their feedback  
regarding the necessary modifications. The questionnaires  
were completed through interview by occupational health and  
safety experts. The data collection took three Months.  
Confidentiality was maintained and informed consent was  
obtained. The workers were told that the collected data was just  
for the aim of conducting a scientific study and they could  
discontinue participation in the study whenever they wished.  
During training of data collectors and supervisors, issues such  
as the data collection instrument, field methods, inclusion–  
exclusion criteria and recordkeeping we emphasized. The  
researchers coordinated the interview process, and spot-  
checked and reviewed the completed questionnaires on a daily  
basis to ensure the completeness and consistency of the data  
collected. The interview questionnaire was pre-tested on 20  
respondents in order to identify potential problem areas,  
unanticipated interpretations and cultural objections to any of  
the questions. Based on the pre-test results, the questionnaire  
was adjusted contextually.  
Insurance status  
Health training  
Employment status  
Health inspection  
Polyester  
Cotton and polyester  
Other  
Yes  
No  
Type of clothe  
Water consumption  
Ratio of rest/work  
75 % work + 25 % rest 257 (14.3)  
0 % work + 50 % rest 341 (18.9)  
5 % work + 75 % rest 1202 (66.8)  
5
2
Yes  
No  
<
1
2
Yes  
No  
Yes  
No  
;
each hour  
81 (4.5)  
1719 (95.5)  
117 (6.5)  
753 (41.8)  
584 (32.4)  
346 (19.2)  
459 (25.5)  
1341 (74.5)  
1373 (76.2)  
427 (23.7)  
Alcohol consumption  
BMI  
18.5  
8.5-24.9  
5-29.9  
30  
Cigarette smoking  
Experience of heat-  
related illnesses  
2
.3 Data analysis  
Data was analyzed using SPSS software version 19.  
Table 2 shows Frequency of Type of HRI in each of studied  
outdoor workplace workers. The highest prevalence of HRI is  
vertigo in construction workers (55 workers). The highest  
prevalence of HRI is headache in farmer workers (253  
workers). The highest prevalence of HRI is headache in rancher  
workers (65 workers). The highest prevalence of HRI is  
headache in brick industries workers (65 workers). In this  
study, the prevalence rate of HRI was 76.2 % in outdoor  
workplace workers in hot and dry of Iran. The highest  
prevalence HRI is headache in all of studied workers (36%).  
The prevalence of HRI is different among studied outdoor  
workplace workers, as shown in Figure 2. Results of this study  
showed that HRI is highest prevalence in agricultural workers  
(37%).  
Descriptive statistics were reported for each variable. The  
normality of each variable was then tested using Kolmogorov-  
Smirnov test with the error rate of ≥0.05. Chi-square and  
Pearson tests were used to determine factors associated with  
HRI. The odds ratio (OR) was also presented with a 95 %  
confidence interval (CI) for significant variables. For multiple-  
comparison, Bonferroni correction was conducted by dividing  
the original α-value by the number of analyses on the dependent  
variable.  
3
Results  
Table 1 shows the demographic and job characteristics of  
the outdoor workplace workers in hot and dry areas of Iran. The  
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Journal of Environmental Treatment Techniques  
2021, Volume 9, Issue 1, Pages: 253-258  
Table 2: Frequency of Type of heat-related illnesses in each of studied outdoor workplace workers  
Frequency and (percent) of illness in each of jobs  
Type of heat-related  
illnesses  
Construction  
workers (%)  
Agricultural  
workers (%)  
Brick industries  
(%)  
Total (%)  
Ranchers (%)  
Syncope  
Seizures  
4 (0.29)  
4 (0.29)  
19 (1.39)  
8 (0.59)  
0 (0.00)  
1 (0.07)  
7 (0.51)  
4 (0.29)  
30 (2.2)  
17 (1.2)  
Heat stroke  
Heat cramps  
Heat exhaustion  
Vomiting  
Headache  
Vertigo  
23 (1.68)  
22 (1.61)  
48 (3.51)  
24 (1.76)  
47 (3.44)  
55 (4.02)  
227 (16.61)  
31 (2.27)  
41 (3.00)  
41 (3.00)  
16 (1.17)  
253 (18.51)  
95 (6.95)  
504 (36.87)  
7 (0.51)  
42 (3.07)  
39 (2.85)  
54 (3.95)  
41 (3.00)  
132 (9.66)  
107 (7.83)  
426 (31.16)  
103 (7.5)  
125 (9.1)  
164 (11.9)  
132 (9.6)  
497 (36.2)  
305 (22.2)  
1373 (100)  
23 (1.68)  
21 (1.54)  
51 (3.73)  
65 (4.75)  
48 (3.51)  
216 (15.80)  
Total (%)  
Table 3 presents the relationship between HRI and  
demographic and job characteristics in studied outdoor  
workplace workers. As can be seen, most HRI are significantly  
associated with age, work experience, type of used clothes, and  
ratio of rest/work (p<0.001).  
outdoor workplaces workers (p<0.001). Table 4 presents odds  
ratios for relationship between HRI and other socio-  
demographic and job characteristics that have two-state in  
studied outdoor workplace workers. According to table 4, In  
this study, the rate of HRI including heat exhaustion among  
married workers was 2 times higher than those among single  
ones [OR=1.94, 95 % CI (1.17-2.73)]. The prevalence of HRI  
had an inverse association with health training programs so that  
workers attending health training programs have experienced a  
decrease in heat-related illness compared with other workers  
Syncope  
1%  
2%  
8%  
Seizures  
22%  
that showed in table 4.  
Moreover, Seasonal workers  
9
%
experienced more HRI compared with permanent workers that  
it was more than 2 times higher than permanent workers. As  
can be seen in table 4, the HRI is the highest prevalence in  
workers who don’t drink water. Results of this study showed  
that there is no relationship between HRI and alcohol  
consumption.  
Heat stroke  
Heat cramps  
Heat exhaustion  
Vomiting  
1
2%  
10%  
4
Discussion  
36%  
Results of this study showed that prevalence of HRI was  
75.2 among outdoor workplace workers in hot and dry areas  
Headache  
Vertigo  
%
of Iran. In the study, heat-related illness is highest prevalence  
in agricultural workers (37%). Headache (36 %), vertigo (22  
%
) and vomiting (10 %) have been the most prevalent HRI  
Figure 1: Prevalence of heat-related illnesses among studied outdoor  
workplace workers  
among outdoor workplace worker, respectively. The  
prevalence of HRI among studied workers was significantly  
associated with age, work experience, type of working clothes,  
water consumption, ratio of rest/work, and employment status  
in studied workers. In study of Jeffrey W. Bethel and et al.  
(2014), one of the key findings from this study is that nearly  
Construction  
workers  
16%  
30% of participants reported experiencing two or more HRI  
31%  
symptoms in Oregon (21). Mirabelli et al. (2010) collected  
cross-sectional survey data from 300 Latino men (n = 285) and  
women (n = 15) in 2009 and found that 40% of those working  
in extreme heat experienced symptoms of HRI North  
Carolina.(22). But, in our study, 76.2 % of the studied workers  
participants reported experiencing one or more HRI symptoms.  
The difference in the prevalence rate of HRI can be due to  
factors such as differences in demographic characteristics of  
workers, different sample size, and research method. The most  
important reason for this prevalence difference can be working  
in hot and dry area of Iran that workers are exposed to high  
temperature and low humidity. Many studies have shown that  
the prevalence of heat-related illness in agricultural workers is  
higher than other outdoor workplace workers (23-25). In this  
study, we also reached this result. The probable reason is that  
agricultural workers have more exposure to air temperature,  
low humidity, and radiant heat. Also, the metabolic heat  
generated by human physical activity is higher in agricultural  
workers which caused Increases body temperature  
agricultural  
workers  
Ranchers  
37%  
16%  
Brick industries  
Figure 2: Prevalence of heat-related illnesses according to type of  
outdoor workplace  
According to table 3, results showed that reducing rest time  
increased the prevalence of HRI (p<0.001). The prevalence of  
heat-related illness is lower in workers that use cotton working  
clothes (p<0.001). Increasing body mass index increases heat  
stroke, heat cramps, heat exhaustion, and vertigo in studied  
2
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