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Cited by 41Thermoregulation and physiological responsesUrban Heat Island MitigationClimate Change and Health Impacts

Is Physiological Equivalent Temperature (PET) a superior screening tool for heat stress risk than Wet-Bulb Globe Temperature (WBGT) index? Eight years of data from the Gothenburg half marathon

Thorsson, Sofia, Rayner, David, Palm, Gunnar, Lindberg, Fredrik, Carlström, Eric, Börjesson, Mats, Nilson, Finn, Khorram-Manesh, Amir +1 more·2021·British Journal of Sports Medicine
DOI 10.1136/bjsports-2019-100632
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Abstract

Background: The Wet-Bulb Globe Temperature (WBGT) index is a common tool to screen for heat stress for sporting events. However, the index has a number of limitations. Rational indices, such as the physiological equivalent temperature (PET) and Universal Thermal Climate Index (UTCI), are potential alternatives. Aim: To identify the thermal index that best predicts ambulance-required assistances and collapses during a city half marathon. Methods: Eight years (2010–2017) of meteorological and ambulance transport data, including medical records, from Gothenburg’s half-marathon were used to analyse associations between WBGT, PET and UTCI and the rates of ambulance-required assistances and collapses. All associations were evaluated by Monte-Carlo simulations and leave-one-out-cross-validation. Results: The PET index showed the strongest correlation with both the rate of ambulance-required assistances (R 2=0.72, p=0.008) and collapses (R 2=0.71, p=0.008), followed by the UTCI (R 2=0.64, p=0.017; R 2=0.64, p=0.017) whereas the WBGT index showed substantially poorer correlations (R 2=0.56, p=0.031; R 2=0.56, p=0.033). PET stages of stress, match the rates of collapses better that the WBGT flag colour warning. Compared with the PET, the WBGT underestimates heat stress, especially at high radiant heat load. The rate of collapses increases with increasing heat stress; large increase from the day before the race seems to have an impact of the rate of collapses. Conclusion: We contend that the PET is a better predictor of collapses during a half marathon than the WBGT. We call for further investigation of PET as a screening tool alongside WBGT.

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  • WBGT has several documented deficiencies related in part to overestimation and lower correlations between WBGT and performance/health consequences.

    “Third, the WBGT has several documented deficiencies (e.g. Budd 2008; Thorsson et al. 2021). The deficiencies are related in part to overestimation and lower correlations between WBGT and performance/health consequences.”

    From Forecasting thermal stress for sports tourists at the 2026 FIFA World Cup (2024) · cites this paper as Thorsson et al. 2021

  • Clothing can counteract health and safety risks from WBGT.

    “We acknowledge the WBGT has its limitations such as (1) clothing can counteract health and safety risks”

    From Forecasting thermal stress for sports tourists at the 2026 FIFA World Cup (2024) · cites this paper as Thorsson et al.2021

  • Other indices have proven slightly more predictive of heat illness than WBGT.

    “(3) other indices have proven slightly more predictive of heat illness (Budd 2008; National Weather Service 2023; Thorsson et al.2021).”

    From Forecasting thermal stress for sports tourists at the 2026 FIFA World Cup (2024) · cites this paper as Thorsson et al.2021

  • WBGT measurements are taken in direct sunlight.

    “(2) WBGT measurements are taken in direct sunlight”

    From Forecasting thermal stress for sports tourists at the 2026 FIFA World Cup (2024) · cites this paper as Thorsson et al.2021

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Authors
Thorsson, S., Rayner, D., Palm, G., Lindberg, F., Carlström, E., Börjesson, M., Nilson, F., Khorram-Manesh, A., & Holmer, B.
Affiliations
  • University of Gothenburg (SE)
  • University of South-Eastern Norway (NO)
  • Karlstad University (SE)
Corresponding author
Thorsson, Sofia
ORCID
Venue
British Journal of Sports Medicine
Publisher
BMJ
Published
2020-05-28
Volume
55
Issue
15
Pages
825-830
ISSN
  • 0306-3674 (ISSN-L)
  • 1473-0480
DOI
10.1136/bjsports-2019-100632
OpenAlex
W3030816486
Cited by
41
References
33
Citations by year
2026: 3 · 2025: 6 · 2024: 12 · 2023: 5 · 2022: 6 · 2021: 8 · 2020: 1
FWCI
3.01
Type
journal article
Language
en
Open access
closed
Locations
  • British Journal of Sports Medicine (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Physiology › Thermoregulation and physiological responses
  • Physical Sciences › Environmental Science › Environmental Engineering › Urban Heat Island Mitigation
  • Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Climate Change and Health Impacts
Keywords
physiological equivalent temperature, wet bulb globe temperature, Universal Thermal Climate Index, half marathon, ambulance attendances, thermal comfort index, radiant heat load
MeSH terms
Marathon Running, Adolescent, Adult, Aged, Air, Ambulances, Body Temperature, Body Temperature Regulation, Female, Heat Exhaustion, Humans, Humidity, Male, Middle Aged, Monte Carlo Method, Risk, Running, Skin Temperature, Sunlight, Sweden, Thermosensing, Thermography, Time Factors, Wind, Confidence Intervals, Linear Models, Age Distribution, Sex Distribution, Heat-Shock Response, Heat Stress Disorders, Young Adult

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