scholarly journals Variations in Athlete Heat-Loss Potential Between Hot-Dry and Warm-Humid Environments at Equivalent Wet-Bulb Globe Temperature Thresholds

2020 ◽  
Author(s):  
Jennifer Vanos ◽  
Andrew Grundstein
Keyword(s):  
Heat Loss ◽  
Sports Medicine ◽  
Evaporative Cooling ◽  
Weather Conditions ◽  
Activity Levels ◽  
Maximum Heat ◽  
Wet Bulb Globe Temperature ◽  
Stressful Environment ◽  
Weather Stations ◽  
Globe Temperature

Context: Many organizations associated with sports medicine recommend using wet-bulb globe temperature (WBGT)-based activity-modification guidelines that are uniform across the country. However, there is no consideration about whether the WBGT thresholds are appropriate for different weather conditions, such as warm-humid (WH) relative to hot-dry (HD), given known differences in physiological responses to these environments.Objective: To identify if regions with drier conditions and greater evaporative cooling potential should consider using WBGT activity-modification thresholds that are different from those with more humid weather.Design: Observational study.Setting: Weather stations across the contiguous United States.Main Outcome Measure(s): A 15-year hourly WBGT dataset from 217 weather stations across the contiguous United States was used to identify particular combinations of globe temperature, wet-bulb temperature, and air temperature that produce WBGTs of 27.9°C, 30.1°C, and 32.3°C. A total of 71 302 observations were clustered into HD and WH environmental conditions. From these clusters, maximum heat-loss potential and heat-flux values were modeled at equivalent WBGT thresholds with various activity levels, clothing, and equipment configurations.Results: We identified strong geographic patterns, with HD conditions predominant in the western half and WH conditions predominant in the eastern half of the country. Heat loss was systematically greater in HD than in WH conditions, indicating an overall less stressful environment even at equivalent WBGT values. At a WBGT of 32.3°C, this difference was 11 W∙m−2 at an activity velocity of 0.3 m∙s−1, which doubled for an activity velocity of 0.7 m∙s−1. The HD and WH difference increased with WBGT value, demonstrating that evaporative cooling differences between HD and WH conditions were even greater at a higher, rather than lower, WBGT.Conclusions: The potential heat loss was consistently greater in HD than WH environments despite equal WBGTs. These findings support the need for further clinical studies to determine the appropriate WBGT thresholds based on environment and physiological limits to maximize safety, yet also avoid unnecessary limitations.

scholarly journals Variations in Athlete Heat-Loss Potential Between Hot-Dry and Warm-Humid Environments at Equivalent Wet-Bulb Globe Temperature Thresholds

2020 ◽  
Vol 55 (11) ◽  
pp. 1190-1198
Author(s):  
Jennifer K. Vanos ◽  
Andrew J. Grundstein
Keyword(s):  
United States ◽  
Heat Loss ◽  
Sports Medicine ◽  
Evaporative Cooling ◽  
Activity Levels ◽  
Maximum Heat ◽  
Wet Bulb Globe Temperature ◽  
Stressful Environment ◽  
Weather Stations ◽  
Globe Temperature

Context Many organizations associated with sports medicine recommend using wet-bulb globe temperature (WBGT)-based activity-modification guidelines that are uniform across the country. However, no consideration has been given to whether the WBGT thresholds are appropriate for different weather conditions, such as warm-humid (WH) relative to hot-dry (HD), based on known differences in physiological responses to these environments. Objective To identify if personnel in regions with drier conditions and greater evaporative cooling potential should consider using WBGT-based activity-modification thresholds that differ from those in more humid weather. Design Observational study. Setting Weather stations across the contiguous United States. Main Outcome Measure(s) A 15-year hourly WBGT dataset from 217 weather stations across the contiguous United States was used to identify particular combinations of globe temperature, wet-bulb temperature, and air temperature that produce WBGTs of 27.9°C, 30.1°C, and 32.3°C. A total of 71 302 observations were clustered into HD and WH environmental conditions. From these clusters, maximum heat-loss potential and heat-flux values were modeled at equivalent WBGT thresholds with various activity levels, clothing, and equipment configurations. Results We identified strong geographic patterns, with HD conditions predominant in the western half and WH conditions predominant in the eastern half of the country. Heat loss was systematically greater in HD than in WH conditions, indicating an overall less stressful environment, even at equivalent WBGT values. At a WBGT of 32.3°C, this difference was 11 W·m−2 at an activity velocity of 0.3 m·s−1, which doubled for an activity velocity of 0.7 m·s−1. The HD and WH difference increased with the WBGT value, demonstrating that evaporative cooling differences between HD and WH conditions were even greater at a higher, rather than lower, WBGT. Conclusions Potential heat loss was consistently greater in HD than in WH environments despite equal WBGTs. These findings support the need for further clinical studies to determine the appropriate WBGT thresholds based on environmental and physiological limits to maximize safety while avoiding unnecessary limitations.

scholarly journals Identifying the need for locally-observed wet bulb globe temperature across outdoor athletic venues for current and future climates in a desert environment

2021 ◽  
Author(s):  
Haven Guyer ◽  
Matei Georgescu ◽  
David M Hondula ◽  
Floris Wardenaar ◽  
Jennifer Vanos
Keyword(s):  
Climate Projections ◽  
Design Strategies ◽  
Local Cooling ◽  
Wet Bulb Globe Temperature ◽  
Exertional Heat Illness ◽  
Cooling Design ◽  
Weather Stations ◽  
Globe Temperature ◽  
Sports Venues ◽  
Projected Changes

Abstract Exertional heat illness and stroke are serious concerns across youth and college sports programs. While some teams and governing bodies have adopted the wet bulb globe temperature (WBGT), few practitioners use measurements on the field of play; rather, they often rely on regionally modeled or estimated WBGT. However, urban development-induced heat and projected climate change increase exposure to heat. We examined WBGT levels between various athletic surfaces and regional weather stations under current and projected climates and in hot-humid and hot-dry weather regimes in the southwest U.S. in Tempe, Arizona. On-site sun-exposed WBGT data across five days (07:00–19:00 local time) in June (dry) and August (humid) were collected over five athletic surfaces: rubber, artificial turf, clay, grass, and asphalt. Weather stations data were used to estimate regional WBGT (via the Liljegren model) and compared to on-site, observed WBGT. Finally, projected changes to WBGT were modeled under mid-century and late-century conditions. On-field WBGT observations were, on average, significantly higher than WBGT estimated from regional weather stations by 2.4°C–2.5°C, with mean on-field WBGT across both months of 28.52.76°C (versus 25.83.21°C regionally). However, between-athletic surface WBGT differences were largely insignificant. Significantly higher mean WBGTs occurred in August (30.12.35°C) versus June (26.92.19°C) across all venues; August conditions reached ‘limit activity’ or ‘cancellation’ thresholds for 6–8 hours and 2–4 hours of the day, respectively, for all sports venues. Climate projections show increased WBGTs across measurement locations, dependent on projection and period, with average August WBGT under the highest representative concentration pathway causing all-day activity cancellations. Practitioners are encouraged to use WBGT devices within the vicinity of the fields of play, yet should not rely on weather station estimations without corrections used. Heat concerns are expected to increase in the future, underlining the need for athlete monitoring, local cooling design strategies, and heat adaptation for safety.

Measuring wet bulb globe temperatures at point-of-exertion in worldwide UK military settings: a longitudinal observational study determining the accuracy of a portable WBGT monitor

2020 ◽  
pp. bmjmilitary-2020-001551
Author(s):  
Patricia Falconer Hall ◽  
J Blackadder-Coward ◽  
H Pynn
Keyword(s):  
Feasibility Study ◽  
Large Scale ◽  
Armed Forces ◽  
Weather Conditions ◽  
Paired Data ◽  
Wet Bulb Globe Temperature ◽  
User Input ◽  
Globe Temperature ◽  
Set Up ◽  
The Uk

IntroductionHeat illness among the UK Armed Forces is usually exertional, and therefore preventable, yet the incidence has not reduced since 2011. JSP 539 explicitly states that wet bulb globe temperature (WBGT) should be measured ‘at the location of greatest heat risk’, not ‘that of most convenience’. A handheld WBGT tracker used at point-of-exertion could reduce this incidence if proven to be as accurate as the current in-service device.MethodsLongitudinal observational comparison and equipment feasibility study of the Kestrel 5400 and QUESTemp 34 (QT-34) in worldwide firm base and deployed UK Armed Forces locations. The locations chosen were Kenya, South Sudan, Belize, Tidworth, Aldershot and Brecon. Paired data points of WBGT readings were collected from November 2017 to August 2018 in all weather conditions.ResultsWBGT readings were comparable between the QT-34 and Kestrel 5400 across the UK and overseas. In addition, there was no change in accuracy between readings taken from the Kestrel 5400 when tripod-mounted and handheld. The Kestrel was easy to set up and far less susceptible to resupply or power supply limitations, as it requires no user input for wet bulb temperature, and runs on AA batteries.ConclusionThis equipment feasibility study has shown that the Kestrel 5400 gives an acceptable accuracy and is easier to use than the QT-34. The authors recommend that the Kestrel 5400 is introduced as an adjunct to the QT-34, and its use within the military setting monitored through ongoing comparative data collection in a large-scale proof-of-concept study.

scholarly journals Exertional Heat Illness in American Football Players: When Is the Risk Greatest?

2016 ◽  
Vol 51 (8) ◽  
pp. 593-600 ◽  
Author(s):  
Earl R. Cooper ◽  
Michael S. Ferrara ◽  
Douglas J. Casa ◽  
John W. Powell ◽  
Steven P. Broglio ◽  
...  
Keyword(s):  
Incidence Rate ◽  
Sports Medicine ◽  
National Collegiate Athletic Association ◽  
The United States ◽  
American Football ◽  
Football Players ◽  
Heat Illness ◽  
Wet Bulb Globe Temperature ◽  
Exertional Heat Illness ◽  
Globe Temperature

Context: Knowledge about the specific environmental and practice risks to participants in American intercollegiate football during preseason practices is limited. Identifying risks may mitigate occurrences of exertional heat illness (EHI). Objective: To evaluate the associations among preseason practice day, session number, and wet bulb globe temperature (WBGT) and the incidence of EHI. Design: Descriptive epidemiology study. Setting: Sixty colleges and universities representing 5 geographic regions of the United States. Patients or Other Participants: National Collegiate Athletic Association football players. Main Outcome Measure(s): Data related to preseason practice day, session number, and WBGT. We measured WBGT every 15 minutes during the practice sessions and used the mean WBGT from each session in the analysis. We recorded the incidence of EHIs and calculated the athlete-exposures (AEs). Results: A total of 553 EHI cases and 365 810 AEs were reported for an overall EHI rate of 1.52/1000 AEs (95% confidence interval [CI] = 1.42, 1.68). Approximately 74% (n = 407) of the reported EHI cases were exertional heat cramps (incidence rate = 1.14/1000 AEs; 95% CI = 1.03, 1.25), and about 26% (n = 146) were a combination of exertional heat syncope and heat exhaustion (incidence rate = 0.40/1000 AEs; 95% CI = 0.35, 0.48). The highest rate of EHI occurred during the first 14 days of the preseason period, and the greatest risk was during the first 7 days. The risk of EHI increased substantially when the WBGT was 82.0°F (27.8°C) or greater. Conclusions: We found an increased rate of EHI during the first 14 days of practice, especially during the first 7 days. When the WBGT was greater than 82.0°F (27.8°C), the rate of EHI increased. Sports medicine personnel should take all necessary preventive measures to reduce the EHI risk during the first 14 days of practice and when the environmental conditions are greater than 82.0°F (27.8°C) WBGT.

Can a local weather station be used in place of on-site measurements for heat stress assessment in a sports setting?

2021 ◽  
Author(s):  
Olivia Cahill ◽  
Andrew Grundstein ◽  
Christian Walker ◽  
Earl Cooper
Keyword(s):  
Heat Stress ◽  
Research Question ◽  
Health And Safety ◽  
Subtropical Climate ◽  
Wet Bulb Globe Temperature ◽  
Playing Field ◽  
Weather Stations ◽  
Globe Temperature ◽  
Set Up ◽  
Local Weather

<p>Across the globe, exposure to environmental heat stress may impose increased health and safety hazards to active populations such as athletes and workers. Monitoring heat stress is a key component of a well-designed heat mitigation policy. Yet, the cost of several hand-held heat stress sensors may pose a financial barrier for use in many circumstances. Numerous areas, however, have existing networks of weather stations that could potentially be incorporated into monitoring heat stress. Currently, the Japanese Ministry of the Environment has set up a network of weather stations across the city to monitor environmental conditions in preparation of the 2021 Tokyo Olympic and Paralympic games. Our research question asks how representative are the values recorded at local weather stations (often located over a natural surface) to playing field conditions with various surfaces and microclimate conditions. In the U.S. the WeatherSTEM network has over 600 stations scattered across the country and measures a suite of variables relevant to heat stress including air temperature, humidity, wind speed, solar radiation and models the wet bulb globe temperature (WBGT) values. This study will compare measurements from a local WeatherSTEM station with on-site measurements taken over three different playing surfaces (grass, synthetic turf, and hardcourt tennis) in a humid subtropical climate in Athens, Georgia. U.S. It will also compare WBGT values computed using different models. Our results may provide insight not only for sports but also for the workplace which take place over various surface types and environments.</p>

scholarly journals An Evaluation of Portable Wet Bulb Globe Temperature Monitor Accuracy

2017 ◽  
Vol 52 (12) ◽  
pp. 1161-1167 ◽  
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.

scholarly journals Reply to “Comment on Fitria et al. ‘Environmental and Occupational Risk Factors Associated with Chronic Kidney Disease of Unknown Etiology in West Javanese Rice Farmers, Indonesia’ Int. J. Environ. Res. Public Health, 2020, 17, 4521”

2020 ◽  
Vol 17 (19) ◽  
pp. 7273
Author(s):  
Laila Fitria ◽  
Nurhayati Adnan Prihartono ◽  
Doni Hikmat Ramdhan ◽  
Susan Woskie
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Heat Index ◽  
Unknown Etiology ◽  
Measured Temperature ◽  
Occupational Risk Factors ◽  
Average Heat ◽  
Wet Bulb Globe Temperature ◽  
Weather Stations ◽  
Globe Temperature

Examining the WBGT (Wet Bulb Globe Temperature) profiles in the two study locations was intended to show temperature differences during the week of the study. Information obtained from the weather stations that provide contextual long-term information on heat and humidity also showed temperature differences. The average measured temperature and humidity in the past year from each of these weather stations show an average heat index of 22 °C in Bogor and an average heat index of 32 °C in Karawang. Interpretation of the chronic kidney disease (CKD) and chronic kidney disease of unknown etiology (CKDu) findings was more complicated because we also found that farmers in our two locations reported differences in the use of mechanization in their farming, presumably impacting their workloads.

scholarly journals The Role of Environmental Conditions on Marathon Running Performance in Men Competing in Boston Marathon from 1897 to 2018

2019 ◽  
Vol 16 (4) ◽  
pp. 614 ◽  
Author(s):  
Pantelis Nikolaidis ◽  
Stefania Di Gangi ◽  
Hamdi Chtourou ◽  
Christoph Rüst ◽  
Thomas Rosemann ◽  
...  
Keyword(s):  
Wind Speed ◽  
Weather Conditions ◽  
Marathon Running ◽  
Marathon Runners ◽  
Wet Bulb Globe Temperature ◽  
Generalized Additive Mixed Models ◽  
Additive Mixed Models ◽  
Boston Marathon ◽  
Globe Temperature

This study investigated the effects of weather conditions on male performance during the Boston Marathon from 1897 to 2018. A total of 383,982 observations from 244,642 different finishers were analysed using Generalized Additive Mixed Models. All runners, annual top 100 finishers and annual top ten finishers were considered. Weather conditions, on race day, were: average air temperature (°C), precipitations (mm), wet-bulb globe temperature (WBGT) (°C), wind speed (km/h), wind direction (N, S, W, E) and pressure (hPa). These effects were examined in multi-variable models with spline smooth terms in function of calendar year. Temperature, when increasing by 1 °C, was related to worsened performance for all groups (i.e., by 00:01:53 h:min:sec for all finishers, p < 0.001). Wind coming from the West, compared to wind coming from other directions, was the most favourable for performance of all groups of finishers. Increasing precipitations worsened performances of top 100 (estimate 00:00:04 h:min:sec, p < 0.001) and top 10 finishers (estimate 00:00:05 h:min:sec, p < 0.001). Wind speed, when increasing by 1 km/h, was related to worsened performance for all finishers (estimate 00:00:19 h:min:sec, p < 0.001), but not for top 100 group, where performances were 00:00:09 h:min:sec faster, p < 0.001. Pressure and WBGT were examined in uni-variable models: overall, performances worsened as pressure and WBGT increased. Our findings contributed to the knowledge about the effect of weather conditions on performance level in male marathon runners.

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

2019 ◽  
Vol 16 (15) ◽  
pp. 2684 ◽  
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.

scholarly journals The Heat Strain of Various Athletic Surfaces: A Comparison Between Observed and Modeled Wet-Bulb Globe Temperatures

2017 ◽  
Vol 52 (11) ◽  
pp. 1056-1064 ◽  
Author(s):  
J. Luke Pryor ◽  
Riana R. Pryor ◽  
Andrew Grundstein ◽  
Douglas J. Casa
Keyword(s):  
Environmental Conditions ◽  
Weather Conditions ◽  
Weather Data ◽  
Measurement Variability ◽  
Wet Bulb Globe Temperature ◽  
Athletic Fields ◽  
The Difference ◽  
National Athletic Trainers Association ◽  
Globe Temperature ◽  
Starting Location

Context:  The National Athletic Trainers' Association recommends using onsite wet-bulb globe temperature (WBGT) measurement to determine whether to modify or cancel physical activity. However, not all practitioners do so and instead they may rely on the National Weather Service (NWS) to monitor weather conditions. Objective:  To compare regional NWS WBGT estimates with local athletic-surface readings and compare WBGT measurements among various local athletic surfaces. Design:  Observational study. Setting:  Athletic fields. Main Outcome Measure(s):  Measurements from 2 identical WBGT devices were averaged on 10 athletic surfaces within an NWS station reporting radius. Athletic surfaces consisted of red and black all-weather tracks (track), blue and black hard tennis courts (tennis), nylon-knit artificial green turf, green synthetic turfgrass, volleyball sand, softball clay, natural grass (grass), and a natural lake (water). Measurements (n = 143 data pairs) were taken over 18 days (May through September) between 1 pm and 4:30 pm in direct sunlight 1.2 m above ground. The starting location was counterbalanced across surfaces. The NWS weather data were entered into an algorithm to model NWS WBGT. Results:  Black tennis, black track, red track, and volleyball sand WBGT recordings were greater than NWS estimates (P ≤ .05). When all athletic-surface measurements were combined, NWS (26.85°C ± 2.93°C) underestimated athletic-surface WBGT measurements (27.52°C ± 3.13°C; P &lt; .001). The range of difference scores (−4.42°C to 6.14°C) and the absolute mean difference (1.71°C ± 1.32°C) were large. The difference between the onsite and NWS WBGT measurements resulted in misclassification of the heat-safety activity category 45% (65/143) of the time (= 3.857, P = .05). The WBGT of water was 1.4°C to 2.7°C lower than that of all other athletic surfaces (P = .04). We observed no other differences among athletic surfaces but noted large WBGT measurement variability among athletic playing surfaces. Conclusions:  Clinicians should use an onsite WBGT device to determine environmental conditions and the need for modification of athletic events, especially as environmental conditions worsen. Given the large WBGT variability among athletic surfaces, WBGT measurements should be obtained from each athletic surface.

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