The role of global radiation measured by a light sensor on heat stress assessment

doi:10.1016/S0306-4565(01)00056-0

Journal of Thermal Biology

Volume 26, Issues 4–5, September 2001, Pages 433-436

https://doi.org/10.1016/S0306-4565(01)00056-0 Get rights and content

Abstract

The purpose of this study was to evaluate a new and relatively small (5 mm) light (L) sensor in order to measure global radiation (GR) for use in heat stress assessment. Data were collected during 25 days from three instruments: L, pyranometer (P) and black globe. Analysis of these data revealed the construction of a new model which converted the L data measured in mV to P values measured in W·m⁻² as follows: P=−13.81+0.619L−0.0001278L². The correlation coefficient between P and L was very high (R²=0.933, P<0.001). Therefore, we concluded that the L sensor has the potential to measure GR for use in heat stress assessment.

Introduction

The wet bulb globe temperature (WBGT), developed by Yaglou and Minard (1957) is considered to be the most common heat stress index for describing environmental heat stress for outdoor and indoor use. It has been adapted by the World Health Organization (WHO) and it is in use by the US army for setting limits at US military training exercises in hot weather (Montain et al., 1999; Moran and Pandolf, 1999; Burr, 1991). This index has also been recognized by other organizations for setting limits in industrial plants (National Institute for Occupational Safety and Health, 1986), adopted by sport associations as guidance to prevent heat injury (American College of Sports Medicine, 1996; McCann and Adams, 1997), and as a safety index for workers in different occupations (Chaurel et al., 1993; Froom et al., 1992; Gun and Budd, 1995; Singh et al., 1995). The WBGT is calculated from ambient temperature (T_a), wet bulb temperature (T_w), and black globe temperature (T_g). The T_g is usually measured by a thermometer surrounded by a 6″ blackened sphere, and quantifies the global radiation component of the thermal load. However, measuring T_g is cumbersome in many circumstances for two main reasons. First, T_g measurement requires about 30 min for the instrument to reach equilibrium. Second, the commonly used blackened sphere is of a relatively big size (6″), even though smaller sized spheres are available. Therefore, measuring T_g becomes inconvenient and simply not practical, especially in transient situations. The purpose of this study was to evaluate a new relatively small (5 mm) light sensor to measure global radiation for use in heat stress assessment.

Section snippets

Materials and methods

This database was obtained from a study conducted near Tel Aviv, Israel, during the autumn season (September–October) for 25 days. Global radiation (GR) measurements were collected daily every 15 min from 09 : 00 until 17 : 00. These data were collected from three instruments placed under the open sky at 1 m height: black globe temperature (T_g) using the Vernon-black globe thermometer, EPLAB pyranometer (P), PSP model with sensitivity of 285–2800 nm, and infra-red light (L) sensor (Centro Vision,

Results

The collected data in this study were carried out over a wide range of weather measurements as depicted in Table 1.

Analysis of the daily collected data from these three instruments revealed, that in spite of the different units, the same pattern for P and L occurred during each day, where T_g was slower in its response and lagged behind P and L in its values (Fig. 1). During morning days T_g did not reflect solar radiation (Fig. 1, top panel), whereas in other days T_g accounted for the change

Discussion

In the present study, the newly developed PGR model from light sensor measurements seemed to evaluate global radiation as the correlation coefficient between PGR and global radiation measured by pyranometer is R²=0.933. Although the database for this study was collected only at one location, the range of the measurements for each day was wide as seen in Table 1. Furthermore, since the study was conducted during the autumn, we had many days where the sky was not clear, partly cloudy or

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Cited by (10)

High frequency characters of arc light radiation in micro plasma arc welding with pulsed current
2019, Results in Physics
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This study revealed the relationship between temperature and arc light intensity. D.S. Moran [9] studied the role of global radiation on heat stress assessment by a small light sensor. However, as shown by D.S. Moran [9] and Lee and Na [8], detections of arc light radiations and their changes by arc light sensors could be only focused on one point of arc.
Dynamic variations in distribution of arc light radiation in micro-plasma arc welding with pulsed current (P-MPAW) are complicated, especially, those abnormal variations influenced by high frequency. It can be seen in the study that there are three areas with obvious difference in arc light radiation during micro-plasma arc welding (MPAW). The variations of light radiations and dimensions in arc three areas mainly followed the transient changes in value of pulsed current when frequency was low. However, with an increasing in frequency of pulsed current, these regular dynamic variations following pulsed current were disturbed by high frequency effects, for instance, dynamic inertia effect, high frequency steady effect, and high frequency compression. In addition, resonation phenomenon occurred at some frequency, leading to a large value either in arc light radiation or in arc dimension. Moreover, the transient variations in arc light radiation and arc dimensions were not synchrotrons because of their different dynamic inertia effect.
Wet-bulb globe temperature (WBGT)-its history and its limitations
2008, Journal of Science and Medicine in Sport
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In many, perhaps most, meters the DB sensor is inadequately screened from radiant heat. In other versions56–58 GT has been replaced by radiometers or light sensors to directly measure solar radiation—measurements which Yaglou and Minard21 had evaluated in the 1950s, only to discard them as being ‘of little practical value’ and to substitute GT, which ‘gave all the information needed for integrating radiation and convection’. Small globes equilibrate more rapidly than the standard 15 cm globe (typically 5 min or less instead of 20–30 min), and consequently are more sensitive to transient fluctuations in environmental conditions.
Wet-bulb globe temperature (WBGT) is nowadays the most widely used index of heat stress, yet many users appear to be unaware of its history and its limitations.
History of WBGT: WBGT was invented and first used during the 1950s as one element in a successful campaign to control serious outbreaks of heat illness in training camps of the United States Army and Marine Corps. Control measures based on air temperature and humidity, and applied to all trainees alike, had proved effective but had entailed excessive compliance costs in the form of lost training time. New control measures introduced in 1956 further reduced heat illness and also lost fewer training hours. Crucial innovations were (1) replacing the temperature and humidity measurements with WBGT, which additionally responds to sun and wind, (2) using epidemiologic analyses of casualty records to identify hazardous levels of WBGT and vulnerable trainees, and (3) protecting the most vulnerable trainees by suspending drill at lower levels of WBGT, and by improving their heat tolerance in special conditioning platoons. This campaign has considerable relevance to the prevention of heat illness in sport.
Limitations of WBGT: WBGT's most serious limitation is that environments at a given level of the index are more stressful when the evaporation of sweat is restricted (by high humidity or low air movement) than when evaporation is free. As with all indices that integrate elements of the thermal environment, interpretation of the observed levels of WBGT requires careful evaluation of people's activity, clothing, and many other factors, all of which can introduce large errors into any predictions of adverse effects. Moreover, the accuracy of WBGT is being eroded by measurement errors associated with the omission of the globe temperature, with non-standard instrumentation, and with unsatisfactory calibration procedures. Because of the above limitations WBGT can provide only a general guide to the likelihood of adverse effects of heat. A much clearer assessment can be obtained by measuring the individual elements of the thermal environment, and using those measurements to estimate the requirement for evaporative cooling, the likelihood of achieving it, and more accurate and comprehensive indices of heat stress.
Validation of the environmental stress index (ESI) for physiological variables
2005, Elsevier Ergonomics Book Series
A new environmental stress index (ESI), based on ambient temperature (T_a), relative humidity (RH) and solar radiation (SR), was recently suggested as a potential substitute for the wet-bulb globe temperature (WBGT) index. The purpose of this study was to evaluate and validate ESI for three different physiological variables including rectal temperature (T_re), heart rate (HR), and sweat rate (m_sw). A database was taken from a previous study where 12 young men (21±1 y) served as subjects exposed to 120 min of 12 different combinations consisting of three metabolic rates (rest and treadmill walking at 5 km·h⁻¹ at 0% and 5% grades), two clothing ensembles (BDU and protective MOPP gear) and two outdoor solar radiation levels (shade and open sky). ESI was calculated as follows: ESI=0.63T_a-0.03RH+0.002SR+0.0054(T_aRH)-0.073(0.1+SR)⁻¹.
Significant differences of about 2 units (p<0.05) were found between the ESI calculated in the sun and in the shade for all exposures. Concomitantly, significant differences (p<0.05) were found between m_sw, HR and T_re when measured in the sun and in the shade during all the exercise exposures. Thus, very high correlations (R²>0.838) were found between ESI and T_re, HR, or m_sw. These results indicate that ESI is strongly correlated to the physiological strain, whereby higher stress is reflected in higher strain. Therefore, evaluating heat stress by ESI, which uses the more common, fast response and accurate climatic measures, becomes more predominant.
Evaluation of the environmental stress index (ESI) for different terrestrial elevations below and above sea level
2004, Journal of Thermal Biology
The purpose of this study was to evaluate the recently developed environmental stress index (ESI) for different climatic conditions and terrestrial elevations below and above sea level and to evaluate a new and relatively small (5 mm) infra-red (IR) light sensor for reliability and for measuring global radiation (GR). Meteorological measurements were taken in 3 different climatic zones (hot/wet, hot/dry and extremely hot/dry) at 6 different terrestrial elevations (−386, −200, 35, 375, 960 and 1640 m) for 9 days between 09:00 and 17:00. Meteorological data included ambient temperature, relative humidity, wet bulb temperature, black globe temperature and GR from two instruments: an IR light sensor and a pyranometer. In general, ESI successfully evaluated the impact of climate from the various locations at different terrestrial elevations. Global radiation measurements revealed no significant ( $P < 0.05$ ) differences between measurements by the pyranometer or the IR light sensor. High correlation was found between ESI and the wet bulb globe temperature index when GR was calculated from both the pyranometer ( $R^{2} = 0.933$ ) and the light sensor ( $R^{2} = 0.939$ ). In conclusion, ESI is a valid measure for different terrestrial elevations, and the IR sensors have the potential to measure GR for use in heat stress assessment incorporated in the index.
Evaluation of the environmental stress index for physiological variables
2003, Journal of Thermal Biology
Recently, a new environmental stress index (ESI), based on ambient temperature (T_a), relative humidity and solar radiation, was suggested. ESI was found to be highly correlated to the WBGT index. However, ESI was not correlated with any physiological variable that reflects strain. The purpose of this study was to evaluate ESI for three different physiological variables (rectal temperature (T_re), heart rate (f_c) and sweat rate (m_sw)), and with the physiological strain index (PSI). Twelve young men were exposed outdoors for 12 different experimental combinations consisting of three metabolic rates (rest, moderate and hard exercise intensity), two clothing ensembles (cotton clothing and protective overgarments), and two solar radiation levels (shade and sun). Each exposure lasted 120 min with T_re and f_c being continuously monitored. High correlations (R⩾0.838) were found when statistical analysis was done between ESI and T_re, f_c, m_sw, or PSI, which have the potential to be widely accepted and used universally. However, further studies between physiological variables and ESI obtained from other climatic conditions, different exercise intensities, and additional clothing ensembles need to be evaluated.
Investigating the levels of thermal stress in Kerman city in 2016 using thermal indices: WBGT, ESI, HI, HSI, and SWreq
2018, Journal of Kerman University of Medical Sciences

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The role of global radiation measured by a light sensor on heat stress assessment

Abstract

Introduction

Section snippets

Materials and methods

Results

Discussion

Environmental stresses and strains in an extreme situationthe repair of electrometallurgy furnaces

Int. Arch. Occup. Environ. Health

Predicting increases in skin temperature using heat stress indices and relative humidity in helicopter pilots

Isr. J. Med. Sci.

Effects of thermal, personal and behavioral factors on the physiological strain, thermal comfort and productivity of Australian shearers in hot weather

Ergonomics

Wet bulb globe temperature index and performance in competitive distance runners

Med. Sci. Sports Exerc.