Heat strain and work performance among traffic police officers in Kuala Lumpur


Introduction: The strong El Nino phenomena increase temperature in Malaysia that directly affects the health of traffic police officers who are highly exposed to high temperature and humidity while controlling traffic. Objective: The aim of this study was to determine the association between heat strain and work performance among police traffic officers. Methodology: The study is divided into two parts that is, first, a measurement of heat stress index at five different workstations at Kuala Lumpur during afternoon using wet bulb globe temperature. Second, the survey was distributed to gain information of work performances from the respondent. Result: Findings indicated that the heat stress index at five locations exceeded the threshold limit value ranging from 33.3 to 41.8°C for 75% work and 25% rest. The most prevalent heat strain symptoms were fatigue (57.9%), dizziness (31%), and muscle cramps (16.4%). Results from multiple regression showed that marital status and the perception of heat exposure are significantly associated with work performance after considering socio-demographical data, heat strain symptoms, and work characteristics. Conclusion: Traffic police officers were exposed to a high level of heat and perceived to reduce their work performance.

Keywords: Heat strain, heat stress, work performances

How to cite this article:
Rasdi I, Roni N, Din NF. Heat strain and work performance among traffic police officers in Kuala Lumpur. Ann Trop Med Public Health 2017;10:65-70
How to cite this URL:
Rasdi I, Roni N, Din NF. Heat strain and work performance among traffic police officers in Kuala Lumpur. Ann Trop Med Public Health [serial online] 2017 [cited 2017 Jul 15];10:65-70. Available from: https://www.atmph.org/text.asp?2017/10/1/65/205542

Malaysia’s temperature peaks around 31 and 33°C; however, in 2016, the temperature was increased to 39°C due to El Niño phenomenon.[1] According to the Global Average Temperature, the world temperature has increased by 1.2°C due to the El Nino phenomenon.[2] The increasing air temperature causes prolonged heat waves and gives more direct heat exposure to affected population. As a result, there were 14 cases of heat-related illness in 2016 in Malaysia. Of which, 11 suffered from heat exhaustions and 3 had heat strokes.[3] In 2016, a 23-year old, a male trainee policeman was the first Malaysian victim to die of heat stroke.[4] Malaysian traffic police officers are usually exposed to hot environment that is caused by direct exposure to sunlight. They need to manage congested city roads and heavy traffic on a daily basis. Moreover, they are also involved with routine patrol, road accident investigation, and first aids provision to the road accidents victims. Generally, there are 6000 traffic police officers who are serving in Malaysia. Kuala Lumpur has the highest numbers of traffic police officers compared to other state in this country.[5]

Heat exposure may occur in many work settings. There are two types of heat exposure, which are indoor and outdoor heat exposure. Outdoor heat exposure usually happens when workers are doing work activities under high temperature and high humidity. Sun light is the main source of heat exposure for the outdoor job. Prolonged heat exposure will induce heat stress. If the heat stress is not recognized and treated at an early state, it will cause heat illness and can even be fatal. In previous study, the prevalence of heat stress was found to be 33.3% among outdoor Sudanese police traffic officers.[6] Heat stress is the condition where the body cannot cope with a high temperature of the external environment and the body is unable to cool itself to maintain the normal body core temperature. This usually occurs when a worker is exposed to high temperature and high humidity for a long period of time.[7] In addition, the effect of heat stress not only causes adverse effect to health, but also reduces the productivity of workers. Commonly, work performances can be defined as how well the employees or employers perform at his or her work. Findings of a previous study showed that 18–35% productivity of labor is lost due to working in hot environment that exceed the threshold limit value (TLV) of 28°C with moderate and heavy workloads.[8]

There are a limited number of studies about the effect of heat stress among traffic police officers. Therefore, the purpose of this study is to evaluate the heat exposure and also work performances among traffic police officers. This study determines the association between heat strain and other risk factors with work performances among traffic police officers. The present study will create and publish knowledge on heat exposure and heat stress among traffic police officers. Data can be used as a baseline to develop a heat stress guideline specifically for them. The current study may also increase awareness about the effect of heat stress on their health and work performances.

Materials and Method

Study design and study population

This is a cross-sectional study that was conducted at the Kuala Lumpur Traffic Police Station from January till March 2016 during the El Nino phenomena. The station was located at Jalan Tun H S Lee, Kuala Lumpur Malaysia. It was chosen as this station managed the most congested road traffic in Malaysia. Purposive sampling was applied in this study in which only traffic police officers who were working in point duty unit were involved. These traffic police officers were mainly involved with traffic controlling, road accident investigation, roadblocks, and a few other outdoor activities. They were highly exposed to heat from sunlight for duration up to 8 h daily. The sampling population in this study was Kuala Lumpur traffic police officers who work as point duty personnel. The total populations for traffic police officer who worked as point duty personnel at Kuala Lumpur were 215. The minimum sample size required to get valid results was 154 based on a formula used by Yamane with 95% confidence interval.[9]

Heat exposure measurement

Prior to the actual data collection, briefing about the study and the method of study was given by the investigator to the head of traffic officers. Then, a walk around survey area guided by an acknowledged traffic police officer was conducted at several locations where traffic police officers were expected to be exposed to high heat exposure. Five high risk road junctions were selected.

The Quest Temp 34 Thermal Environment Meter was used to measure and calculate the dry bulb temperature, wet bulb temperature, globe temperature, wet bulb globe temperature (WBGT) outdoor index, relative humidity, and heat index or humidex. The WBGT is a measure of heat stress in direct sunlight that includes humidity, wind speed, sun angle, and cloud cover (infrared radiation). This meter was placed at the selected junctions for 8 h. Data were transferred into a computer for analyses and interpretation using DMS software. The activities of respondents while doing their duties were recorded. The measurement used in this study followed the Standard Operating Procedure (SOP). The SOP is circulated from the NIOSH standard.[7]

Work performance assessment

A Malay self-administered questionnaire was used in this study. Part A was to obtain socio-demographic information from respondent, such as age, race, marital status, education level, monthly income, and body mass index (BMI). Part B was about work characteristics such as the duration of work, work overtime, and total day’s work in a week. Part C was about lifestyle information such as smoking, drinking alcohol, and medical history. Part D was about heat exposure and heat strains information such as the environment at workplace, average work in hot environments, and signs and symptoms of heat strains. The last part, Part E, was about work performance information. The question of work performance information was adapted from the Health Performances Questionnaire developed by World Health Organization.[10] There were seven questions on the level of work performances using the Likert-scale ranging from “never” (1) to “always” (5). A pre-test was conducted among 10% of the respondent to observe and evaluate their level of knowledge and understanding about the questionnaire. Questionnaires and consent letter forms were distributed to all the traffic police officers who worked as point duty personnel at Kuala Lumpur. Each respondent was given 2 months to complete the questionnaire and consent letter forms. The investigator visited the traffic police station after 2 months to collect the returned surveys and consent letter form by the respondent.

Statistical analysis

All data were analyzed by using software SPSS 22 (Statistical Package for Social Science). Since data were not normally distributed, the Kruskal-Walis test was used to compare the level of socio-demographic data, work characteristic, and the perception of heat with work performances, whereas the Mann–Whitney test was used to determine the significant differences between heat strains and work performances.



[Table 1] shows the distribution of socio-demographic of respondents. More than half of the respondents were between the age of 21-30 years (61.4%), married (60.8%), and Malay (88.9%). Considering the education level, most of the respondents completed at least pre-university or obtain an STPM certificate (70.2%). The range family monthly income was between RM 1000-2000 (45%) and RM 2000-3000 (39.2%). Most of the respondents had a normal BMI (54.4%).

Table 1: Socio-demographic background of respondent (N = 171)

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Work characteristic

All respondents work in shifts. In general, the road controlling duties were divided into two working shifts that were morning and evening shifts. The work of traffic officer involved standing, walking, and use hand to control the traffic. The morning shift for traffic controlling was from 6.00 a.m. till 2.00 p.m., whereas the evening shift working time began from 2.00 p.m. till 10.00 p.m. Most of them worked six days in a week (95.9%). The maximum job tenure was 32 years. There were 77.2% of respondents who worked overtime. For the duration of working and rest, most of the respondent worked for 75% of the total working hours and rest for 25% in a day. According to ACGIH, their workload was classified as “moderate” that was based on their work activities.[11]

Wet bulb globe temperature

The reading of WBGT was taken at five different locations based on the point duties given by the representative of traffic police officers. The result shows that the mean ± SD of WBGT outdoor for five different locations was 37.00 ± 2.98. The maximum temperature was 41.8°C and the minimum temperature was 33.3°C. See p [Table 2].

Table 2: Descriptive of wet bulb globe temperature (WBGT)

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Perception of heat

Most of the respondents (94.2%) agreed that their working environment is exposed to heat. Due to the heat environment, more than half of the respondent (60.2%) experienced discomfort at the work place. The survey about the perception of heat shows that 61.4% of respondent perceived that their working environment was hot.

Heats strain symptoms

[Table 3] shows that more than half (57.9%) of total respondent experienced fatigue. For other heat strain symptom such as dizziness, queasiness, muscle cramps, and fainting, most of the respondent claimed that they do not experience or have such symptoms.

Table 3: Heat strain symptoms, descriptive (N = 171)

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Work performances

More than half of the respondents (63.8%) perceived that their performance was no higher than their co-workers. Some respondents (27.5%) perceived that most or all of the time their work performance was lower than most of their work. Only a small number of them perceived that most or all of the time, they did no work at times when they were supposed to be working (5.9%), they were not working as carefully as they should (17.5%), their work quality was lower than they should be (7%), they did not concentrated enough on their job (8.2%), and their health limit their work (5.8%).

Relationship between independent variables and work performances

Kruskal-Wallis Test, Mann-Whitney U test, Pearson Correlation Test, or Spearman Rank correlation tests were run to find the relationship between independent variables and work performances. Results showed that socio-demographic factor such as age, race, education level, monthly income and BMI did not significantly associated with work performances among traffic police officers. Marital status was found significantly correlated with work performance where married respondents had higher work performances than single respondents (rs = 0.28, P = 0.02). With regard to work characteristics, there were no significant relationships between the duration of work, total day work in a week, and the duration of working and rest and work performances. There was a significant association between work overtime (Z = −2.644 and ρ = 0.008) and work performances in such a way that work overtime led to lower job performances of the respondents.

For heat perception, there was no significant relationship between comfortability at the workplace due to heat environment and their perception whether their work environment is hot or not and work performance. However, results showed that those who perceived that their work exposed them to hot environment had lower work performance than those who perceived that their work did not exposed them to heat (r = −0.35 and P < 0.01). With reference to heat strain, results showed that there was no significant difference in work performance among those who had dizziness, queasiness, or fainting and those who did not have such symptoms. However, findings indicated that respondents those who experienced heat strain symptoms of fatigue (Z = −2.91 and ρ = 0.004) and muscle cramp (Z = −2.146 and ρ = 0.032) had poorer work performance than those who did not have such symptoms. In summary, bivariate analyses showed that there was a significant relationship between work overtime, perception that their work exposed them to heat, and symptoms of fatigue and muscle cramps and work performance.

Multivariate regression predicting for work performance

Seven independent variables were included in the multiple linear regression for predicting work performance. Marital status, work overtime, perception of heat exposure, fatigue, and muscle cramp that were found significantly related to work performance in bivariate analyses were included. Other variables, age and education levels and smoking status were also included as they were found in previous studies to be significant in predicting work performances. Results showed that after considering several factors including age, educational level, smoking status, and heat strain symptoms, marital status and perceived heat exposure were significantly associated with work performance. Respondents who were single (ρ = 0.27) and respondents who claimed that they were working in uncomfortably hot environment (ρ = −0.33) had poorer work performance than respondents who were married and those who perceived that their working environment was not hot. This model explained 23.5%, F(7, 64) = 2.81 of the total variance in work performance. [Table 4].

Table 4: Multiple regression for predicting work performance

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The result clearly showed that the WBGT of the respondents exceeded the TLV (28.5°C) for 75% work and 25% rest proposed by the ACGIH.[11] According to this standard that is fully adopted by Malaysia, those respondents were exposed to the hazardous level of heat and were at risk to get heat-related illnesses. Consistent with the results from ambient temperature measurements, results of the present study indicated that most respondents (94.2%) agreed that their working environment is exposed to heat and more than half of them (60.2%) experienced discomfort at the work place due to hot working environment.

Findings also indicated that the most prevalent heat strain symptoms were fatigue (57.9%), dizziness (31%), and muscle cramps (16.4%). These figures were higher than those found among Japanese traffic controllers during summer where the prevalence of fatigue was 24.5% and the prevalence of dizziness and muscle cramps were 11.8%.[12] This difference can be explained by looking at the WBGT results, where the WBGT in Japan (30.5°C) was lower than the WBGT found in the present study. The WBGT found in Khartoum, Sudan (23.15 to 26.40ºC) was also lower than the results of the present study.[6]

In total, 94.2% of the respondents agreed that the most significant factors for predicting work performance after considering socio-demographical factors, work characteristics, heat exposure, and heat strain were only marital status and their perception of heat exposure. This study revealed that married respondents performed better than single respondents. The positive effect of being married to work performance was shown in a number of previous studies.[13],[14] Van Oudenhoven et al. suggested that married workers tend to be more satisfied with their life and psychologically healthier.[14]

Also, results of the present study indicated that respondents who reported that their working environment were hot had lower work performance than those who reported that their working environment was not hot. These findings were consistent with the results of a previous study among construction workers.[15] Moreover, findings of a previous study among global working population suggested that work capacity significantly declined as the reading of WBGT exceed, between 26 and 30°C.[16] He suggested that in a very hot environment when heat gain is more than heat loss the body temperature begins to rise and results in health illness and loss of concentration while working. In another perspective, Brake proposed that in high temperature, workers try to adapt to this condition; hence, they rest more and work less that subsequently reduces their work productivity.[17]


The respondents were exposed to heat higher than the permissible exposure limit, and this exposure was perceived to reduce their work performance. Findings of this study call for further studies to explore the other potential factors that may affect their work performance. Intervention studies are therefore warranted to reduce their heat exposure and thus improve their work performances.


We acknowledge the Royal Malaysian Police and Universiti Putra Malaysia for their support in completing this research.

Ethical issues

The ethical approval of this study was obtained from Ethic Committee, Universiti Putra Malaysia.

Financial support and sponsorship


Conflicts of interest:

There are no conflicts of interest.

Malaysia Meteorological Department (2016). Equinoks dan cuaca panas di Malaysia. Official Portal Available from: http://www.met.gov.my/ [Last accessed on 2016 Mar 11].
National Oceanic Atmospheric Administration (NOAA) (2016). Global Average Temparature (GAT). Available from: http://www.noaa.gov/february-global-temperature-anomaly-sets-new-recordglobe [Last accessed on 2016 Mar 17].
Sahar, F.M. (2016). News Straight Times Online. 14 cases of heat exhaustion and heat stroke recorded so far: Health Ministry. Available from: http://www.nst.com.my/news/2016/03/133523/14-cases-heat-exhaustion-and-heat-stroke-recorded-so-far-health-ministry [Last accessed on 2016 Mar 13].
The Stright Times (2016). Trainee cop first to die of heatstroke in Malaysia. Available from: http://www.straitstimes.com/asia/se-asia/trainee-cop-first-to-die-of-heatstroke-in-malaysia [Last accessed on 2016 Mar 19].
Polis Diraja Malaysia (2016). Laman Utama. Retrieved from Polis Diraja Malaysia. Available from: http://www.rmp.gov.my/laman-utama [Last accessed on 2016 Apr 23].
Ibrahim AF, Ahmed AA, Salih AI. Heat stress among traffic police officers at North Khartoum Locality, Sudan. Int J Sci Res 2015;4:2357-9.
NIOSHNIOSH criteria for a recommended standard occupational exposure to heat and hot environment. US: DHHS (NIOSH) Publication; 2016.
Chinnadurai J, Venugopal V, Kumaravel P, Paramesh R. Influences of occupational heat stress on labour productivity—a case study from Chennai, India. J Prod Perform Manag 2014;2:245-55.
Yamane T. Statistics: An introductory analysis. New York: Harper and Row; 1973.
Kessler RC, Barber C, Beck AL, Berglund PA, Cleary PD, McKenas D, et al. The World Health Organization Health and Work Performance Questionnaire (HPQ). J Occup Environ Med 2016;45:156-74.
ACGIH. Heat Stress and Strain: TLV® Physical Agents. Documentation. 7th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists; 2009.
Inaba R, Mirbod SM. Comparison of subjective symptoms and hot prevention measures in summer between traffic control workers and construction workers in Japan. Ind Health 2007;45:91-9.
Selmer J, Lauring J. Marital status and work outcomes of self-initiated expatriates: is there a moderating effect of gender? Cross Cultural Management. Int J 2011;18:198-13.
Van Oudenhoven JP, Mol S, Van der Zee KI. Study of the adjustment of Western expatriates in Taiwan ROC with the multicultural personality questionnaire. Asian J Soc Psychol 2003;6:159-70.
Hanna AS, Taylor CS, Sullivan KT. Impact of extended overtime on construction labor productivity. J Constr Eng Manag 2005:131-734-9.
Kjellstrom T, Kovats RS, Lloyd SJ, Holt T, Tol RSJ. The direct impact of climate change on regional labor productivity. Arch Environ Occup Med 2009;64:217-27.
Brake DJ. The deep body core temperatures, physical fatigue and fluid status of thermally stressed workers and the development of thermal work limit as an index of heat stress [dissertation]. Perth, Australia: School of Public Health, Curtin University; 2002.

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ATMPH.ATMPH_77_17


[Table 1], [Table 2], [Table 3], [Table 4]

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