Print this page Email this page
Users Online: 877
Home About us Editorial board Search Browse articles Submit article Instructions Subscribe Contacts Login 

Previous article Browse articles Next article 
ORIGINAL ARTICLE
Int J Env Health Eng 2015,  4:37

Investigating relationship between perceptual strain index with indices heat strain score index, wet bulb globe temperature in experimental hot condition


1 Department of Occupational Health Engineering, Student Research Center, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran
2 Department of Occupational Health Engineering, School of Health, Isfahan University of Medical Sciences, Isfahan; Environment Research Center, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran

Date of Web Publication30-Nov-2015

Correspondence Address:
Dr. Habibollah Dehghan
Department of Occupational Health Engineering, School of Health, Isfahan University of Medical Sciences, Hezar Jerib Ave., Isfahan
Iran
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2277-9183.170704

Rights and Permissions
  Abstract 

Aims: The purpose of the present study was to investigating relationship between perceptual strain index (PeSI) with indices heat strain score (HSSI), wet bulb globe temperature (WGBT) in experimental hot condition.
Materials and Methods: This study in five different temperature conditions (21°C, 24°C, 27°C, 30°C, and 35°C) was carried out on 15 male students in the climate chamber and on the treadmill with three levels of the activity. The thermal sensation and perceived exertion was recorded for calculating PeSI, and HSSI questionnaire was completed.
Results: Pearson correlation test showed a high correlation (r = 0.84) between the PeSI and HSSI (P = 0.001). Also, Pearson correlation test showed between PeSI with WBGT and air temperature, respectively, a good correlation (r = 0.76) and high correlation (r = 0.81) (P = 0.001).
Conclusion: The findings of the study showed that the PeSI can be used for evaluating heat strain in the absence of access to other methods of evaluating heat stress since it has an acceptable correlation with valid indices of heat stress. Also, easy application and quick and cost is much less than other evaluating heat strain indices.

Keywords: Climate chamber, heat strain score index, perceptual strain index


How to cite this article:
Sartang AG, Dehghan H. Investigating relationship between perceptual strain index with indices heat strain score index, wet bulb globe temperature in experimental hot condition. Int J Env Health Eng 2015;4:37

How to cite this URL:
Sartang AG, Dehghan H. Investigating relationship between perceptual strain index with indices heat strain score index, wet bulb globe temperature in experimental hot condition. Int J Env Health Eng [serial online] 2015 [cited 2021 Sep 20];4:37. Available from: https://www.ijehe.org/text.asp?2015/4/1/37/170704


  Introduction Top


Thermal stress affects workers in workplace. Heat can have a negative impact on production efficiency and health of workers at work, occupational diseases and accidents of work.[1] Also in many countries, workplace exposure to heat is used as an occupational health problem and exposure to heat can cause illnesses such as heat exhaustion, heat cramps, heat shock, heat fatigue, heat stroke, and death.[2] Heat stress occurs when the body's means of controlling its internal temperature starts to fail. As well as air temperature, factors such as work rate, humidity and clothing worn while working may lead to heat stress. Therefore, it may not be obvious to someone passing through the workplace that there is a risk of heat stress. The heat stress is a serious threat in many industries including steel, petrochemicals, and glass, and also in road construction and it can affect directly the performance and health of people.[3] A study conducted by researchers at the Indian automobile industry concluded that more than 28% of workers in the various processes of the industry are working with a risk of exposure to heat stress.[4] Many heat strain indices have been developed by researchers to evaluate heat strain. Indices developed to assess the heat strain have some disadvantages, and a single index cannot be used to evaluate the heat strain in environments with different climate conditions, or some of the indices have variables difficult and time-consuming to be measured or are expensive and costly. The physiological strain due to heat stress includes core body temperature, skin temperature, and heart rate. Physiological strain index is also a method of evaluation of heat stress in the workplace.[5] On the other hand, of the existing methods for assessing the risk of heat stress, the observational and perceptional methods have been continuously developed and used because of their simplicity and inexpensiveness, rapid answers, and feasibility to be used without interfering with the workplaces. One of the observational perceptual techniques presented recently to evaluate the thermal strain is observational technique and perceptual heat strain score index (HSSI). The HSSI scale includes 17 items, observation and subjective questions, relating to heat stress such as thermal and humidity sensation and heat strain assessment included three levels of risk, without heat strain (score less than 13.5), the medium of heat strain (13.6 to 18) and high heat strain (>18.1).[6] Another index is based on individual perception of that thermal presented perceptual strain index (PeSI). Tikuisis et al. have developed PeSI that measures the thermal strain in individuals through the thermal sensation and the Borg Rating of Perceived Exertion. This index is indeed a method to assess the risk of thermal strain through perception. PeSI is a simple and inexpensive method to evaluate the thermal strain and it can be used to determine the health risks to workers exposed to heat.[7] Many heat stress indices have been developed and these indices have some disadvantages.[2] The purpose of this study is to investigate the relationship between PeSI with indices HSSI and wet bulb globe temperature (WBGT) in experimental hot condition.


  Materials and Methods Top


This experimental study was performed on 15 male students in the climate chamber. The sampling method was the invitation of the subjects, considering inclusion criteria for the study. Inclusion criteria were a lack of cardiovascular diseases, hypertension, neurological diseases, and musculoskeletal diseases, consuming coffee and caffeine for 12 h before the test. The subjects were informed about the test procedures, and a signed participation consent form was obtained from all participants. The selection and number of samples were based on the similar empirical studies.[5],[7] After selecting individuals, at the end of 10 min rest, persons in out-of-climate chamber, variables thermal sensation and rating of perceived exertion, and also HSSI questionnaire were recorded. WBGT index and air temperature were also recorded. After resting, the individual performed a physical activity (walking) in five different thermal stages with WBGT 21°C, 24°C, 27°C, 30°C, and 35°C each for 45 min. Based on a similar study, each thermal stage was executed in a separate day, including a 45-min physical activity on a treadmill.[7] The subject engaged in physical activity on a treadmill at each of the above temperatures for the first 15 min at the rate of 2.4 kph (light physical activity), the second 15 min at the rate of 4.8 kph (medium physical activity), and the third 15 min at the rate of 6.3 kph (heavy physical activity).[1] The physical activity was performed with cotton clothes (0.6 clo). And at the end of each 15 min session and at each of above speeds and temperatures, the thermal sensation and rating of perceived exertion by the subject were recorded to calculate the PeSI and also questionnaire HSSI, in each of the velocities and temperatures completed. Finally, WBGT and air temperature at the end of each 15 min were recorded.

The PeSI is calculated as follows:[7]

PeSI = 5 × ([TS − 1]/4) + 5 × (PE/10)

The score for thermal sensation and perceived exertion is presented in [Table 1] and [Table 2].
Table 1: Thermal sensation score

Click here to view
Table 2: Perceived exertion score

Click here to view


The final score for the PeSI is from 0 to 10, and is presented in [Table 3].
Table 3: The final score the perceptual strain index

Click here to view


Environmental temperature was monitored using the WBGT apparatus of Casella model, Britain, with a sensitivity of 0.1°C. The air temperature was monitored using a thermometer. The results from the study were analyzed using SPSS, version 18, IBM Company manufacture and finally, using Pearson correlation test and regression analysis. This study was performed after getting permission from the Ethics Committee in Medicine and Participant's informed about the test procedures.


  Results Top


Participant's characteristics in this study were 15 men with a mean and standard deviation (SD) of 26.43 ± 1.47 years old, 179.66 ± 9.11 cm height, 75.21 ± 3.99 kg weight, and 24.18 ± 3.86 kg/m 2 body mass index.

The mean and SDs of the studied indices are presented in [Table 4].
Table 4: Mean and SD of the studied indices and relevant variables

Click here to view


Pearson correlation test showed that there is a high correlation between the PeSI and the HSSI (r = 0.84) (P = 0.001).

The linear regression curve in [Figure 1] shows a high correlation between the PeSI and HSSI, so that the PeSI will increase when the HSSI increases.
Figure 1: The linear regression analysis between the perceptual strain index and the heat strain score index

Click here to view


Pearson correlation test showed that there is a good correlation between the PeSI and WBGT (r = 0.76) (P = 0.001).

The linear regression curve in [Figure 2] shows relationship between the PeSI and WBGT. There is a good correlation between these two indices that the PeSI increases with WBGT.
Figure 2: The linear regression analysis between the perceptual strain index and wet bulb globe temperature

Click here to view


Pearson correlation test showed that there is a high correlation between the PeSI and air temperature (r = 0.81) (P = 0.001).

The linear regression curve [Figure 3] shows the relationship between the PeSI and air temperature. There is a high correlation between these two indices that air temperature increases with PeSI.
Figure 3: The linear regression analysis between the perceptual strain index and air temperature

Click here to view



  Discussion Top


In most industries, and lack of protection against heat stress is a major threat to human health and productivity in the workplace. The results of this study showed that both subjective and perceptual individuals can detect heat stress under different temperature conditions. Each of the heat stress indices has limitations, for example, WBGT is expensive and time consuming. Malchaire et al. concluded that the WBGT index is not an ideal screening method.[8] Rastogi et al. in a study that examined the relationship between WBGT and heart rate of the glass workers concluded that WBGT alone is not sufficient to evaluate the thermal strain.[9] At this study, there is a significant correlation between PeSI and HSSI. Dehghan et al. examined the observational-perceptional index as HSSI in the form of a questionnaire and concluded that participants have a good subjective perception of the heat stress in workplaces, and the obtained score of this index has a significant correlation with WBGT index which is consistent with the findings of the present study.[10] Gallagher et al. developed a perceptual hyperthermia index based on a laboratory pilot. They concluded that there was a direct significant correlation between the perceptual hyperthermia index and different air temperatures, and they had also a good subjective perception of the heat, which is consistent with the findings of the present study.[11] Habibi et al. concluded in a study on the relation between WBGT index and the HSSI among women that increase in WBGT will increase HSSI which is consistent with the findings of the present study.[12] Dehghan et al. studied and validated the thermal strain questionnaire focused on women in workers at the hot weather in field and concluded that participants have a correct perceptual and subjective response of the heat stress, which is consistent with the findings of the present study.[13] Haruyama et al. studied participants' subjective judgment of the thermal stress using subjective judgment scale and concluded a direct significant correlation between subjective judgment scale and WBGT, so that the scores from the subjective judgment scale is increased by increasing the WBGT. Participants had a proper perception of the heat, which is consistent with the findings of the present study.[14] Habibi et al. concluded in a study on the relation between the PSI and the HSSI among women that the increase in the PSI will increase the thermal strain index. The participants showed a proper subjective response to the heat stress, which is consistent with the findings of the present study.[15]


  Conclusion Top


The results of this study showed that the PeSI is highly correlated with HSSI and air temperature. In this study, the correlation between PeSI with PeSI is higher than the WBGT index, indicating that PeSI compared with WBGT index has greater ability to evaluate the thermal strain. On the other hand, the application of this index is quick and easy, and the cost is much less. In fact, evaluating the thermal strain by the PeSI is a cheap and simple method and can also be used to determine the health risks of workers exposed to heat and in the risk assessment of thermal strain.

Acknowledgments

This study was conducted in the Climate Chamber, School of Health, Isfahan University of Medical Sciences Research Project and an article was extracted from the master's thesis. The authors would like to thank Mrs. Peymaneh Habibi, the engineer and director in the laboratory chamber of thermal stresses for her sincere cooperation during the study.

Isfahan University of Medical Science.

Financial support and sponsorship

Isfahan University of Medical Science.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Golmohammadi R, Amirabadi M. Air Conditioning control in Workplace. Hamedan University of medical science edition. 2012. p. 124-170. {Persian}.  Back to cited text no. 1
    
2.
Golbabaee F, Omidvari M. Man and thermal stress work environments. Tehran University edition. 2002. P. 80-90, 190-225.  Back to cited text no. 2
    
3.
Jafari MJ, Hoorfarasat G, Salehpour S, Khodakarim S, Haydarnezhad N. Comparison of Correlation between Wet Bulb Globe Temperature, Physiological Strain Index and Physiological Strain Index Based on Heart Rate with Heart Rate and Tympanic Temperature on Workers in a Glass Factory. Journal of Safety Promotion and Injury Prevention 2014;2:55-64. e-ISSN: 2383-1901 p-ISSN: 2345-2455.  Back to cited text no. 3
    
4.
Ayyappan R, Sankar S, Rajkumar P, Balakrishnan K. Work-related heat stress concerns in automotive industries: a case study from Chennai, India. Global Health Action 2009;2:18-26.  Back to cited text no. 4
    
5.
Moran DS, Shitzer A, Pandolf KB. A physiological strain index to evaluate heat stress. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 1998;275:R129-R34.  Back to cited text no. 5
    
6.
Dehghan H, Habibi E, khodarahmi B, Yousefi Hasan, Hasanzadeh Akbar. A Survey of the Relationship of Heat Strain Scoring Index and Wet Bulb Globe Temperature Index with Physiological Strain Index among Men in Hot Work Environments. Journal of Health System Research 2012:7.255-266.  Back to cited text no. 6
    
7.
Tikuisis P, Mclellan TM, Selkirk G. Perceptual versus physiological heat strain during exercise-heat stress. Medicine & Science in Sports & Exercise 2002;34:1454-61.  Back to cited text no. 7
    
8.
Malchaire J, Gebhardt H, Piette A. Strategy for evaluation and prevention of risk due to work in thermal environments. Annals of occupational hygiene 1999;43:367-76.  Back to cited text no. 8
    
9.
Rastogi S, Gupta B, Husain T. Wet-bulb globe temperature index: a predictor of physiological strain in hot environments. Occupational Medicine 1992;42:93-7.  Back to cited text no. 9
    
10.
Dehghan H, Mortazavi SB, Jafari MJ, Meraci MR, Khavanin A. Designing and Investigating Content Validity and Reliability of A Questionnaire for Preliminary Assessment of Heat Stress at Workplace. Journal of Health System Research 2012;7:300-310.  Back to cited text no. 10
    
11.
Gallagher Jr M, Robertson RJ, Goss FL, Nagle-Stilley EF, Schafer MA, Suyama J, et al. Development of a perceptual hyperthermia index to evaluate heat strain during treadmill exercise. European journal of applied physiology 2012;112:2025-34.  Back to cited text no. 11
    
12.
Habibi P, Dehghan H, Rezaei S, Maghsoudi K. Relationship between physiological strain index and wet bulb globe temperature index in women in the climate chamber. Journal of Health System Research 2014;8:1-3.  Back to cited text no. 12
    
13.
Dehghan H, Habibi E, Habibi P, Maracy MR. Validation of a Questionnaire for Heat Strain Evaluation in Women Workers. International journal of preventive medicine 2013;4:631.  Back to cited text no. 13
    
14.
Haruyama Y, Muto T, Matsuzuki H, Ito A, Tomita S, Muto S, et al. Evaluation of subjective thermal strain in different kitchen working environments using subjective judgment scales. Industrial health 2010;48:135-44.  Back to cited text no. 14
    
15.
Habibi P, Dehghan H, Rezaei S, Maghsoudi K. Thermal, physiological strain index and perceptual responses in Iranian Muslim women under Thermal Condition in order to Guide in Prevention of Heat Stress. Iranian Journal of Health, Safety and Environment 2014;1:172-6.  Back to cited text no. 15
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

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



 

Top
Previous article  Next article
 
  Search
 
Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

 
  In this article
Abstract
Introduction
Materials and Me...
Results
Discussion
Conclusion
References
Article Figures
Article Tables

 Article Access Statistics
    Viewed1984    
    Printed129    
    Emailed0    
    PDF Downloaded240    
    Comments [Add]    

Recommend this journal