Wet bulb Globe Temperature White Paper

Wet Bulb Globe Temperature Thresholds 2012 / White paper

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Summary

Executive summary .................................................................................... p 1

Introduction ................................................................................................ p 2

Who uses the wet bulb globe temperature indicator? .................................. p 4

State-of-the-art of wet bulb globe temperature ............................................ p 6

User benefits with Schneider Electric’s industry-unique solution ................... p 8

Conclusion ................................................................................................. p 9

Executive summary

Heat stress is a common challenge to athletes and a significant safety issue for

their trainers, coaches and managers. Professional sport organizations, including

the National Collegiate Athletic Association (NCAA) and the National Athletic

Trainers Association (NATA), recommend they follow safety protocols based on

wet bulb globe temperature thresholds. Some state high school associations are

identifying fines for violations of wet bulb globe temperature thresholds to

enforce compliance.

While there are dedicated sensors for determining wet bulb globe temperature,

they are expensive and single-purpose and do not provide any information beyond

the wet bulb globe temperature at the time of reading. Schneider Electric’s

popular MxVision WeatherSentry Online® service now includes the wet bulb globe

temperature reading for the user’s location, using a scientifically-based calculation.

It also provides wet bulb globe temperature forecasts, based on its own industry-

best temperature forecasts, along with proactive alerts based on the user’s

specified thresholds. It is the first and only marketed service that provides wet bulb

globe temperature forecasts and alerts that help the organization prepare and/

or revise training and practice schedules and activities as needed to comply with

relevant safety protocols.

This unique functionality eliminates the need for the organization to purchase,

deploy and maintain expensive equipment specific for wet bulb globe temperature

determination. Its inclusion in the notably reliable Schneider Electric weather

information service further supports decision making by those responsible for

athlete safety.

White paper on Wet Bulb Globe Temperatures | 01

Wet Bulb Globe Temperature Thresholds

Introduction

Wet bulb globe temperature is a composite temperature indicator, calculated

using a formula that factors the effect of temperature, humidity, wind speed, and

solar radiation on humans. It is a more comprehensive measure than the heat

index, or ‘feels-like factor’, which reflects air temperature and relative humidity

measured in the shade. The heat index commonly is referred to as the human-

perceived equivalent temperature — ‘how hot it feels’ — to a person who is

normally dressed and not involved in strenuous activity.

Yet, because the wet bulb globe temperature calculation reflects measurements

taken in the sun and embraces wind, cloud cover and sun angle, wet bulb globe

temperature is considered the better measure of heat stress on the human body.

In this paper, we discuss how the wet bulb globe temperature indicator is used

by sports organizations and why Schneider Electric’s weather information service

provides the wet bulb globe temperature measurement that best meets their

safety protection needs.



An unmatched service offering to protect all athletes

Who uses the wet bulb globe temperature indicator?The Women’s Tennis Association (WTA), National

Athletic Trainers Association (NATA) and National

Collegiate Athletic Association (NCAA) all identify

both wet bulb globe temperature and heat index in

their respective rules and procedures as acceptable

metrics for decision-making purposes; see Table 1.

However, wet bulb globe temperature is fast

becoming the most widely used and accepted index

for the assessment of heat stress in sports and

turf activities, from student-level up to professional

organizations; see Table 2. It also is used in military

operations, and the federal Occupational Safety and

Health Administration (OSHA) maintains heat safety

protocols based on wet bulb globe temperature

thresholds that provide guidance to outdoors-

focused sectors, such as construction operations.

Essentially, anyone who works or exercises in direct

sunlight should monitor wet bulb globe temperature.

Studies reveal there is an increase in the number

of heat-related injuries when the wet bulb globe

temperature reaches/exceeds 82 degrees Fahrenheit.



Organization Wet Bulb Globe

Temperature

decision points, in

degrees Fahrenheit

Heat Index

decision points,

in degrees

Fahrenheit

WTA 86.2, 90 93, 104.2

NATA 65, 73, 82 87, 90, 115

NCAA 75, 82 77, 87

National Weather

Service

Not used 90, 104, 126

Table 1Wet bulb globe temperature — a new standard for measuring environmental heat stress

Wet Bulb Globe Temperature

Heat Index

Measured in the sun

a x

Measured in the shade

x a

Uses temperature

a a

Uses relative humidity

a a

Uses wind a x

Use cloud cover

a x

Uses sun angle

a x

Who uses the wet bulb globe temperature indicator, continued…



* Adopted on March 19, 2012, by the State Executive Committee and goes into effect for the 2012-13 school year.

Table 2Georgia High School Association (GHSA) Practice Policy for Heat and Humidity*

Wet Bulb Globe

Temperature Reading

Activity Guidelines & Rest Break Guidelines

Under 82.0 Normal activities — provide at least three separate

rest breaks each hour of minimum duration of three

minutes each during workout

82.0 — 87.0 Use discretion for intense or prolonged exercise;

watch at-risk players carefully; provide at least three

separate rest breaks each hour of a minimum of

four minutes duration each

87.0 — 89.9 Maximum practice time is two hours. For football:

players restricted to helmet, shoulder pads, and

shorts during practice. All protective equipment

must be removed for conditioning activities. For all

sports: provide at least four separate rest breaks

each hour of a minimum of four minutes each

90.0 — 92.0 Maximum length of practice is one hour, no

protective equipment may be worn during practice

and there may be no conditioning activities. There

must be 20 minutes of rest breaks provided during

the hour of practice.

Over 92.1 No outdoor workouts; cancel exercise; delay

practices until a cooler wet bulb globe temperature

reading occurs.

In 2012, the Georgia High School Association

(GHSA) passed new laws* defining statewide policy

for conducting practices and voluntary conditioning

workouts in all sports during times of extremely high

heat and/or humidity:

• Rest time should involve both unlimited hydration

intake (water or electrolyte drinks) and rest

without any activity involved

• For football, helmets should be removed during

rest time

• The site of the rest time should be a ‘cooling

zone’ and not in direct sunlight

• When the wet bulb globe temperature reading is

over 86:

• Ice towels and spray bottles filled with ice

water should be available at the ‘cooling zone’

to aid the cooling process

• Cold immersion tubs must be available for

practices for the benefit of any player showing

early signs of heat illness

Schools violating the heat policy can be fined from

$500 to $1000 per occurrence.

State-of-the-art of wet bulb globe temperatureTraditionally, organizations measure wet bulb globe temperature with expensive,

on-site sensors that provide the temperature indicator at the moment, for

the specific location of the sensor, with no visability to future wet bulb globe

temperature readings. The accuracy of these sensors can vary.

Now, Schneider Electric’s popular MxVision WeatherSentry Online weather

information service incorporates not only wet bulb globe temperature

observations, but also reliable wet bulb globe temperature forecasts and alert

notifications that help organizations adhere to safety guidelines:

• Observations — the user can view the observed wet bulb globe temperature

for a specific area, calculated using peer-reviewed, published methodology

that does not rely on specialized sensors.1 These observations are displayed

within the site’s layered map, as shown in Figure 1.



Figure 1MxVision WeatherSentry Online provides a wet bulb globe temperature map layer for observed wet bulb globe temperature.

1 Estimation of Black Globe Temperature for Calculation of the Wet Bulb Globe Temperature Index. Proceedings of the World Congress on Engineering and Computer Science 2011, Vol II WCECS 2011, October 19-21, 2011, San Francisco, USA.

State-of-the-art of wet bulb globe temperature, continued…



• Forecasts — forecasts for wet bulb globe

temperature are available in hourly and daily

forecasts; see Figure 2. Schneider Electric is the

first and only service to make available hourly

wet bulb globe temperature forecasts out to

72 hours. It also provides daily wet bulb globe

temperature forecasts out to 15 days, for long-

term planning purposes.

• Alerts — proactive alerts based on the user’s

wet bulb globe temperature thresholds are

delivered to the user’s computer or mobile device

via patented, location-specific technology;

see Figure 3. Many users set up observation

or forecast alerts based on NCAA, NATA, or

other established heat safety protocols. These

alerts provide the lead time necessary to

adjust schedules as needed to assure athlete

safety. Again, alerts based on wet bulb globe

temperature forecasts are exclusive to Schneider

Electric’s MxVision WeatherSentry Online service.

Figure 2Exclusive from Schneider Electric, hourly and daily wet bulb globe temperature forecasts allow sports managers to plan when activities might be limited due to the heat.

Figure 3A proactive alert notifies the user, via computer or mobile device, when the wet bulb globe temperature exceeds or is expected to exceed the organization’s identified threshold.

User benefits with Schneider Electric’s industry-unique solution



Accuracy. A recent, independent study conducted

by ForecastWatch.com identified Schneider Electric

as the most accurate temperature forecaster among

leading providers for Day 1 and Day 2 temperature

forecasts. This study signals the fifth consecutive

year Schneider Electric has been ranked best in

temperature forecast accuracy. These temperature

forecasts are a key element in the service’s industry-

unique wet bulb globe temperature forecasts.

Reliability. The MxVision WeatherSentry Online service

eliminates the need for the organization to purchase

and maintain expensive, single-function equipment.

Efficiency. With hourly wet bulb globe temperature

forecasts provided for 72 hours out, the sports

organization is able to plan effectively and realize the

most efficiency in conducting its training and practice

activities and competitive events.

Around-the-clock online meteorological consulting.

Users can submit a weather-related question

to Schneider Electric’s team of professional

meteorologists and receive a response back within

15 minutes. For example, the user might ask “What

is your confidence in the wet bulb globe temperature

forecast between 2 to 4 p.m. today, which calls for

the wet bulb globe temperature to be higher than 82

degrees?” See Figure 4.

Figure 4Online consulting allows users to contact professional meteorologists to gain expert insight to specific weather questions and concerns.

Conclusion

Wet bulb globe temperature solutions, in summary:

• Wet bulb globe temperature is being adopted by more sports organizations as

their standard for identifying possible heat-related risks to athletes.

• It better represents the potential of environmental heat stress than does the

traditional heat index indicator, because it factors the wind, cloud and

sun-angle factors significant when athletes are exerting themselves at a facility

with no sun cover.

• Thousands of sports and recreation organizations — including high school,

university, and professional sports teams — already rely on Schneider Electric’s

real-time weather conditions and reliable forecasts to ensure player, spectator,

and employee safety.

• This service now includes current and forecasted wet bulb globe temperature

readings, along with proactive alerting to notify users when their specified

thresholds exist or are forecast.

• This industry-unique functionality, along with all other current and forecast

weather information provided to help protect athletes, spectators and staff,

makes the Schneider Electric weather service a comprehensive solution

that provides value far beyond that delivered by dedicated wet bulb globe

temperature equipment.



Schneider Electric USA, Inc.

9110 West Dodge RoadOmaha NE 68114 Tel: 800-610-0777Fax: 402-255-8125www.schneider-electric.com/us ©

2012

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July 2012

Wet bulb Globe Temperature White Paper

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