Prevalence of Heat-Related Illnesses among Outdoor Workplaces Workers in Hot and Dry Areas of Iran

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

Milad Derakhshanjazari , Ali Jangjou , Roohollah Bagherzadeh , Mohammad Reza

Monazzam , Zahra Zamanian

Department of Occupational Health Engineering, School of Health, Shiraz University of Medical Sciences, Shiraz, Iran

Emergency Medicine Department, Shiraz University of Medical Sciences, Shiraz, Iran

Department of Textile Engineering, Advanced Textile Materials and Technology Research Institute (ATMT), Amirkabir University

of Technology, Tehran, Iran

Department of Occupational Health Engineering, Tehran University of Medical Sciences, Tehran, Iran

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

995 to 2005 (15). In Japan, 389 deaths occurred from 1989-

012 due to heat shocks (16). The reports indicate the

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

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

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.

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.

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

.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.

1-40

1-60

Age (Years)

Married

Single

Primary education

Secondary education

Associate degree

1-4

5-9

10-14

≥

Yes

Seasonal

Permanent

Yes

Cotton

Marital status

Education level

Work experience

(Years)

.2 Data collection tools and quality control

Data was collected by researcher-made questionnaire

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

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)

Yes

≥

Yes

;

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

Cigarette smoking

Experience of heat-

related illnesses

.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.

Results

Table 1 shows the demographic and job characteristics of

the outdoor workplace workers in hot and dry areas of Iran. The

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)

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)

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

Seizures

22%

that showed in table 4.

Moreover, Seasonal workers

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

10%

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

Journal of Environmental Treatment Techniques

2021, Volume 9, Issue 1, Pages: 253-258

Table 3: The association between overall heat-related illnesses and demographic characteristics of the outdoor workplaces workers

Type of heat-related illnesses

Heat

stroke

Heat

cramps

Heat

exhaustion

Variables

Syncope

Seizures

Vomiting

Headache

Vertigo

N(%)

≤

1-40

41-60

0 (0.0)

1 (3.3)

19 (63.3)

10 (33.3)

<0.001

4 (23.5)

2 (11.7)

7 (41.3)

>0.05

16 (15.5)

9 (8.7)

41 (39.8)

37 (35.9)

<0.001

6 (4.8)

22 (13.4)

32 (19.5)

31 (18.9)

79 (48.2)

<0.001

29 (22.0)

27 (20.5)

34 (25.8)

42 (31.8)

>0.05

41 (8.2)

36 (7.2)

226 (45.5)

194 (39.0)

<0.001

56 (18.4)

49 (16.1)

137(44.9)

63 (20.7)

>0.05

27 (21.6)

59 (47.2)

33 (26.4)

<0.001

Age (Years)

p-value

Primary

7 (56.7)

(30)

7 (41.3)

6 (35.3)

4 (23.5)

>0.05

34 (34)

59 (57.3)

10 (9.7)

>0.05

69 (55.2)

21 (16.8)

13 (10.4)

<0.001

57 (34.8)

43 (26.2)

64 (39.0)

>0.05

46 (34.8)

47 (35.6)

39 (29.5)

>0.05

112 (22.5)

204 (41.0)

181 (36.4)

<0.001

76 (24.9)

145(47.5)

84 (27.5)

>0.05

education

Secondary

education

Associate

degree

Education

level

(13.3)

p-value

<0.001

5-9

-4

16 (53.3)

5 (16.7)

4 (13.3)

<0.001

0 (0.0)

9 (53)

67 (65)

30 (29.1)

3 (3)

30 (24)

33 (26.4)

37 (29.6)

25 (20)

<0.001

5 (4)

39 (23.8)

53 (32.3)

30 (18.3)

42 (25.6)

<0.001

56 (42.4)

32 (24.2)

27 (20.5)

17 (12.9)

<0.001

234 (47.1)

103 (20.7)

62 (12.5)

98 (19.7)

<0.001

132(43.3)

53 (17.4)

69 (22.6)

51 (16.7)

<0.001

Work

experience

3 (17.7)

4 (23.5)

1 (0.6)

<0.001

3 (17.7)

5 (29.4)

10-14

≥15

p-value

Cotton

Polyester

(Years)

3 (3)

<0.001

19 (18.4)

21 (20.4)

53 (32.3)

73 (44.5)

31 (23.5)

35 (26.5)

56 (11.3)

194 (39.0)

44 (14.4)

89 (29.2)

9 (30)

33 (26.4)

Type of

working

clothes

Cotton and

polyester

Other

11 (36.7)

6 (35.3)

23 (22.3)

29 (23.2)

21 (12.8)

41 (31.1)

176 (35.4)

64 (21.0)

12 (40)

<0.001

3 (17.7)

>0.05

40 (38.8)

<0.001

62 (49.6)

<0.001

17 (10.4)

<0.001

25 (18.9)

>0.05

71 (14.3)

<0.001

108(35.4)

<0.001

p-value

5 % work +

5 % rest

0 % work +

0 % rest

5 % work +

5 % rest

8 (93.3)

1 (3.3)

(3.3)

11 (64.7)

2 (11.8)

3 (17.7)

41 (39.8)

45 (43.7)

17 (16.5)

103(82.4)

3 (2.4)

98 (59.8)

45 (27.4)

21 (12.8)

55 (41.7)

57 (43.2)

20 (15.2)

312 (62.8)

83 (16.7)

102 (20.5)

201(65.9)

57 (18.7)

47 (15.4)

Ratio of

rest/work

19 (15.2)

p-value

18.5

8.5-24.9

25-29.9

p-value

Statistically significant at p<0.05

<0.001

10 (33.3)

3 (10)

14 (46.7)

>0.05

<0.001

3 (17.7)

2 (11.8)

4 (23.5)

9 (53)

<0.001

6 (5.8)

3 (2.9)

39 (37.9)

55 (53.4)

<0.001

21 (16.8)

17 (13.6)

36 (28.8)

51 (40.8)

<0.001

26 (15.9)

27 (16.5)

12 (7.3)

99 (60.4)

<0.001

32 (24.2)

31 (23.5)

46 (34.8)

23 (17.4)

>0.05

111 (22.3)

109 (21.9)

173 (34.8)

104 (20.9)

>0.05

53 (17.4)

61 (20.0)

67 (22.0)

124(40.7)

<0.001

BMI

≥

>0.05

Table 4: Odds ratios of exposure to heat-related illnesses based on two-state variables

OR ( %95 CI)

Variables

Heat

stroke

1.33 (1.17- 3.1 (1.8-

Heat

cramps

Heat

Syncope

Seizures

Vomiting

Headache

Vertigo

exhaustion

1.94 (1.17-

2.73)^*

Marital status

1.05 (0.55-

1.7)

0.91 (0.23-

1.55)

1.73 (1.09-

2.64)^*

3.23 (1.97-

4.58)^*

1.56 (0.79-

2.27)

(Married, Single)

1.6)^*

.87

0.51-

.29)

4.25)^*

1.79

(0.91-

2.22)

0.41

(0.25-

0.74)*

2.33

(1.70-

3.15)*

0.74

(0.30-

1.30)

0.17

(0.12-

0.24)*

0.97

(0.51-

1.55)

1.71

(0.96-

2.90)

Insurance status

0.88

(0.52-1.31)

1.08

(0.71-1.57)

1.62

(1.09-3.10)*

1.62

(0.81-3.00)

1.67

(0.85-2.96)

1.18

(0.88-1.94)

(

(Yes, No)

.36

0.17-

.59)*

0.24

Health training

0.41

(0.24-0.51)*

0.23

(0.13-0.36)*

0.52

(0.37-0.71)*

0.28

(0.17-0.41)*

1.21

(0.19-2.34)

(

(0.06-

0.44)*

2.52

(1.6-

3.74)*

(Yes, No)

Employment status

Seasonal,

2.21

(1.81-

2.26)*

.71

4.03

(2.88-5.84)*

7.71

(5.12-11.7)*

5.05

(3.12-7.06)*

2.71

(1.5-3.36)*

(

(1.83-3.73)*

Permanent)

.12

0.58-

.69)

Health inspection

1.81

1.64

1.77

(1.05-3.03)*

2.33

(1.25-4.86)*

0.97

(0.49-2.01)

1.18

(0.36-1.87)

(

(Yes, No)

(1.07-3.22)* (0.77-3.57)

.32

0.20-

.41)*

0.11

(0.06-

0.14)*

0.10

(0.02-

0.19)*

Water consumption

Yes, No)

0.22

(0.11-0.29)*

0.09

(0.06-0.13)*

0.42

(0.22-0.60)*

0.30

(0.23-0.45)*

(

.33

alcohol consumption

Yes, No)

1.31

(0.54-2.18)

1.02

(0.69-1.90)

0.77

(0.65-1.13)

1.79

(0.91-2.90)

0.90

(0.65-1.35)

1.00

(0.28-1.61)

(0.73-

(

.36)

.26

1.59

(1.15-

2.02)*

Cigarette smoking

Yes, No)

1.25 (0.89-

2.09)

0.94

(0.42-2.00)

0.90

(0.56-1.60)

1.16

(0.66-1.66)

0.79

(0.65-0.85)*

(0.17-

(

.27)

*Statistically significant at p<0.05

Journal of Environmental Treatment Techniques

2021, Volume 9, Issue 1, Pages: 253-258

In a study Jeffrey W. Bethel and et al , heavy sweating

Funding

(

50%) and headache (24%) were the most commonly reported

symptoms (21). In our study, headache (36%) is the highest

prevalence of HRI symptoms among outdoor workplaces

workers in hot and dry areas of Iranian. These different results

are probably due to differences in the type of nutrition, working

time, and physiological characteristics of workers. In a study

by Roh Allahparvari and his colleagues in 2015, they

researched four examples of workers' working clothes with

low, medium, and high workload and their most important

result was that working clothe with 100% cotton textile was

recommended for low-hard workload, and working clothes

with textile 69.8% polyester and 30.2% cotton for medium-

hard workload was recommended for Iranian workers (26). It

was also reported in our study that type of working clothes

made of different textiles have effect on prevalence of HRI in

outdoor workplace workers. Probably, clothing interferes with

humans’ ability to regulate the thermal balance with the

environment and lose heat to the environment which has been

confirmed in many studies (27, 28).

The author(s) received financial support for the research,

authorship, and/or publication of this article: This study as a

Ph.D. degree thesis (code: 20825) was supported by Shiraz

University of Medical Sciences.

Ethical issue

Authors are aware of, and comply with, best practice in

publication ethics specifically with regard to authorship

(

avoidance of guest authorship), dual submission, manipulation

of figures, competing interests and compliance with policies on

research ethics. Authors adhere to publication requirements

that submitted work is original and has not been published

elsewhere in any language.

Competing interests

The authors declare that there is no conflict of interest that

would prejudice the impartiality of this scientific work.

June T. Spector and et al. (2016) reported that risk factors

for HRI symptoms in Washington crop workers, decreased age

and less work experience), piece rate pay, and longer distance

to the toilet were associated with self-reported HRI symptoms

29). In the present study reported same results that less work

Authors’ contribution

All authors of this study have a complete contribution for

data collection, data analyses and manuscript writing.

(

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