Heat Index and Adjusted Temperature as Surrogates for Wet Bulb Globe Temperature to Screen for Occupational Heat Stress

Abstract Extreme heat is annually the deadliest weather hazard in the U.S. and is strongly amplified by climate change. In Florida, summer heat waves have increased in frequency and duration, exacerbating negative human health impacts on a state with a substantial older population and industries (e.g., agriculture) that require frequent outdoor work. However, the combined impacts of temperature and humidity (heat stress) have not been previously investigated. For eight Florida cities, this study constructs summer climatologies and trend analyses (1950–2020) of two heat stress metrics: heat index (HI) and wet bulb globe temperature (WBGT). While both incorporate temperature and humidity, WBGT also includes wind and solar radiation, and is a more comprehensive measure of heat stress on the human body. With minor exceptions, results show increases in average summer daily maximum, mean, and minimum HI and WBGT throughout Florida. Daily minimum HI and WBGT exhibit statistically significant increases at all eight stations, emphasizing a hazardous rise in nighttime heat stress. Corresponding to other recent studies, HI and WBGT increases are largest in coastal subtropical locations in Central and South Florida (i.e., Daytona Beach, Tampa, Miami, Key West), but exhibit no conclusive relationship with urbanization changes. Finally, danger (103–124°F) HI and high (> 88°F) WBGT summer days exhibit significant frequency increases across the state. Especially at coastal locations in the Florida Peninsula and Keys, danger HI and high WBGT days now account for > 20% of total summer days, emphasizing a substantial escalation in heat stress, particularly since 2000.

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An Evaluation of Portable Wet Bulb Globe Temperature Monitor Accuracy

Journal of Athletic Training ◽

10.4085/1062-6050-52.12.18 ◽

2017 ◽

Vol 52 (12) ◽

pp. 1161-1167 ◽

Cited By ~ 7

Author(s):

Earl Cooper ◽

Andrew Grundstein ◽

Adam Rosen ◽

Jessica Miles ◽

Jupil Ko ◽

...

Keyword(s):

Physical Activity ◽

Heat Stress ◽

Sports Medicine ◽

Pearson Correlation ◽

Heat Stroke ◽

Heat Index ◽

Mean Bias Error ◽

Bias Error ◽

Wet Bulb Globe Temperature ◽

Globe Temperature

Context: Wet bulb globe temperature (WBGT) is the gold standard for assessing environmental heat stress during physical activity. Many manufacturers of commercially available instruments fail to report WBGT accuracy. Objective: To determine the accuracy of several commercially available WBGT monitors compared with a standardized reference device. Design: Observational study. Setting: Field test. Patients or Other Participants: Six commercially available WBGT devices. Main Outcome Measure(s): Data were recorded for 3 sessions (1 in the morning and 2 in the afternoon) at 2-minute intervals for at least 2 hours. Mean absolute error (MAE), root mean square error (RMSE), mean bias error (MBE), and the Pearson correlation coefficient (r) were calculated to determine instrument performance compared with the reference unit. Results: The QUESTemp° 34 (MAE = 0.24°C, RMSE = 0.44°C, MBE = –0.64%) and Extech HT30 Heat Stress Wet Bulb Globe Temperature Meter (Extech; MAE = 0.61°C, RMSE = 0.79°C, MBE = 0.44%) demonstrated the least error in relation to the reference standard, whereas the General WBGT8778 Heat Index Checker (General; MAE = 1.18°C, RMSE = 1.34°C, MBE = 4.25%) performed the poorest. The QUESTemp° 34 and Kestrel 4400 Heat Stress Tracker units provided conservative measurements that slightly overestimated the WBGT provided by the reference unit. Finally, instruments using the psychrometric wet bulb temperature (General, REED Heat Index WBGT Meter, and WBGT-103 Heat Stroke Checker) tended to underestimate the WBGT, and the resulting values more frequently fell into WBGT-based activity categories with fewer restrictions as defined by the American College of Sports Medicine. Conclusions: The QUESTemp° 34, followed by the Extech, had the smallest error compared with the reference unit. Moreover, the QUESTemp° 34, Extech, and Kestrel units appeared to offer conservative yet accurate assessments of the WBGT, potentially minimizing the risk of allowing physical activity to continue in stressful heat environments. Instruments using the psychrometric wet bulb temperature tended to underestimate WBGT under low wind-speed conditions. Accurate WBGT interpretations are important to enable clinicians to guide activities in hot and humid weather conditions.

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Assessment of Heat Stress Exposure among Construction Workers in the Hot Desert Climate of Saudi Arabia

Annals of Work Exposures and Health ◽

10.1093/annweh/wxz033 ◽

2019 ◽

Vol 63 (5) ◽

pp. 505-520 ◽

Cited By ~ 12

Author(s):

Mohammed Al-Bouwarthan ◽

Margaret M Quinn ◽

David Kriebel ◽

David H Wegman

Keyword(s):

Saudi Arabia ◽

Heat Stress ◽

Heat Exposure ◽

Construction Workers ◽

Heat Index ◽

Stress Exposure ◽

Construction Sites ◽

Excessive Heat ◽

Wet Bulb Globe Temperature ◽

Globe Temperature

Abstract Objectives Excessive heat exposure poses significant risks to workers in hot climates. This study assessed the intensity and duration of heat stress exposure among workers performing residential construction in southeastern Saudi Arabia (SA) during the summer, June–September 2016. Objectives were to: identify work factors related to heat stress exposure; measure environmental heat exposure at the construction sites; assess the heat stress risk among workers using the wet bulb globe temperature (WBGT) index; and determine if temperature-humidity indices can be appropriate alternatives to WBGT for managing heat stress risk at the construction sites. Methods Worksite walkthrough surveys and environmental monitoring were performed, indoors and outdoors, at 10 construction sites in Al-Ahsa Province. A heat stress exposure assessment was conducted according to the American Conference of Governmental Industrial Hygienists (ACGIH®) guidelines, which uses the WBGT index. WBGT measurements from two instruments were compared. Alternative heat stress indices were compared to the WBGT: the heat index (HI) and humidex (HD) index. Results Construction workers were exposed to excessive heat stress, indoors and outdoors over a large part of the work day. Complying with a midday outdoor work ban (12–3 p.m.) was not effective in reducing heat stress risk. The highest intensity of exposure was outdoors from 9 a.m. to 12 p.m.; a period identified with the highest hourly mean WBGT values (31–33°C) and the least allowable working time according to ACGIH® guidelines. Comparison of the alternative indices showed that the HI is more reliable than the HD as a surrogate for the WBGT index in the climate studied. Conclusion The extreme heat exposure represents a serious risk. The severity of heat stress and its impact are projected to increase due to climate change, emphasizing the need for immediate improvement of the current required protective measures and the development of occupational heat stress exposure guidelines in SA.

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Heat Warnings in Switzerland: Reassessing the Choice of the Current Heat Stress Index

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph16152684 ◽

2019 ◽

Vol 16 (15) ◽

pp. 2684 ◽

Cited By ~ 4

Author(s):

Annkatrin Burgstall ◽

Ana Casanueva ◽

Sven Kotlarski ◽

Cornelia Schwierz

Keyword(s):

Heat Stress ◽

Added Value ◽

Heat Index ◽

Stress Index ◽

Stress Indices ◽

Wet Bulb Globe Temperature ◽

Human Stress ◽

Weather Stations ◽

Globe Temperature ◽

Heat Stress Index

High temperatures lead to heat-related human stress and an increased mortality risk. To quantify heat discomfort and the relevant dangers, heat stress indices combine different meteorological variables such as temperature, relative humidity, radiation and wind speed. In this paper, a set of widely-used heat stress indices is analyzed and compared to the heat index currently used to issue official heat warnings in Switzerland, considering 28 Swiss weather stations for the years 1981–2017. We investigate how well warnings based on the heat index match warning days and warning periods that are calculated from alternative heat stress indices. The latter might allow for more flexibility in terms of specific warning demands and impact-based warnings. It is shown that the percentage of alternative warnings that match the official warnings varies among indices. Considering the heat index as reference, the simplified wet bulb globe temperature performs well and has some further advantages such as no lower bound and allowing for the calculation of climatological values. Yet, other indices (e.g., with higher dependencies on humidity) can have some added value, too. Thus, regardless of the performance in terms of matches, the optimal index to use strongly depends on the purpose of the warning.

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New and Old Indices for Evaluating Heat Stress in an Indoor Environment: Some Considerations. Comment on Kownacki, L.; Gao, C.; Kuklane, K.; Wierzbicka, A. Heat Stress in Indoor Environments of Scandinavian Urban Areas: A Literature Review. Int. J. Environ. Res. Public Health 2019, 16 (4), 560. doi:10.3390/ijerph16040560

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph16081444 ◽

2019 ◽

Vol 16 (8) ◽

pp. 1444 ◽

Cited By ~ 2

Author(s):

Francesco Chirico ◽

Nicola Magnavita

Keyword(s):

Heat Stress ◽

Urban Areas ◽

Heat Index ◽

Indoor Environments ◽

Wet Bulb Globe Temperature ◽

Comfort Index ◽

Predicted Heat Strain ◽

Thermal Work ◽

Globe Temperature ◽

Heat Indices

In their review, Kownacki et al. showed some practical and easy to use workplace heat indices that are useful for indoor environments, namely the “Wet Bulb Globe Temperature” (WBGT), the “Predicted Heat Strain” (PHS) model, the “Thermal Work Limit” (TWL), the “Equivalent Temperature” (ET) and the thermal comfort index “PMV/PPD”. In this letter, the authors explain why the modified PMV/PPD method together with the indices combining temperature with humidity, such as the “Humidex Index” and the “Heat Index”, could be a more feasible and useful tool for evaluating potential thermal stress in indoor environments for both the occupational and general population.

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Ergonomics of the thermal environment. Assessment of heat stress using the WBGT (wet bulb globe temperature) index

10.3403/30311329 ◽

2017 ◽

Keyword(s):

Heat Stress ◽

Thermal Environment ◽

Temperature Index ◽

Wet Bulb Globe Temperature ◽

Environment Assessment ◽

Globe Temperature

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EFFECTS OF INONIZING RADIATION CAUSED HEAT STRESS ON THE HUMAN BODY FOR STANDARD ISO 7243

Journal of Medicine and Pharmacy ◽

10.34071/jmp.2013.1.7 ◽

2013 ◽

pp. 47-57

Author(s):

Van Trong Le ◽

Thi Tuyet Mai Nguyen ◽

Thi Xuan Duyen Nguyen ◽

Ba Luan Nguyen ◽

Tuyen Pham ◽

...

Keyword(s):

Heat Stress ◽

Risk Assessments ◽

Management Systems ◽

Temperature Index ◽

Wet Bulb Globe Temperature ◽

Simple Index ◽

Simple Tool ◽

Results Management ◽

Globe Temperature ◽

Hot Environments

Objectives: Presents heat stress Standard ISO 7243, which is based upon the wet bulb globe temperature index (WBGT), and considers its suitability for use worldwide. Materials and Methods: The WBGT index are considered and how it is used in ISO 7243 and across the world as a simple index for monitoring and assessing hot environments. Results: Management systems, involving risk assessments, that take account of context and culture, are required to ensure successful use of the standard and global applicability. For use outdoors, a WBGT equation that includes solar absorptivity is recommended. A ‘clothed WBGT’ is proposed to account for the effects of clothing. Conclusion: ISO 7243 is a simple tool to assess the heat stress and may be applicated worldwide.

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