When you want to know why to use WBGT as a Heat Stress Indicator, it’s important to first look at what WBGT is.  WBGT is based on an equation where a combination of environmental factors are used to calculate a reading.  The calculation used measures the heat stress in direct sunlight.  This type of reading also takes into account the temperature, wind speed, humidity, the angle of the sun and the solar radiation (or simply, the cloud cover).  This isn’t the same as what is called the “heat index”, which is just the temperature and humidity, as calculated for shady areas.  WBGT is used by military agencies and the Occupational Safety and Health Administration (OSHA) as a guide for managing workload in direct sunlight.

One of the most widely accepted and preferred methods of measuring heat stress is through regular monitoring of the WBGT of the environment.  This is most often done using a small handheld device like the Kestrel 4400, which tracks the most important atmospheric readings.

There are many sports organizations that also utilize WBGT to access the potential risk for environmental stress on athletes, an issue that has been a growing point of concern for many parents and coaches of youth sports.  Some of the organizations include the National Athletic Trainers Association (NATA0, National Collegiate Athletic Association (NCAA) and the Women’s Tennis Association (WTA). 

When Measuring WBGT is Important

WBGT is important throughout the year, but it is especially important when it comes to preventing heat-related injuries and illness in pre-season practice sessions and games.  Players need 10-14 days to let their bodies fully acclimate to their environment, and if an athlete doesn’t take enough time to prepare, they could potentially be putting themselves at risk for heat stroke.  WBGT provides coaches, athletic trainers and those who work in sports medicine with a solid point of reference to use when making big decisions that may affect a player's health. 

WBGT as a heat stress indicator is typically viewed in a range that goes from low levels of risk on up to extreme or hazardous levels of risk.  When it comes to high school athletics, a WBGT reading of under 82.0 is generally assumed to be ok for outdoor workouts as long as water and breaks are given.  Anything over a 92 means that all outdoor activities must be cancelled.  No more questioning if conditions really are safe enough for practice or for games – when coaches and other staff have an accurate view into what WBGT is and why it is important when it comes to measuring heat stress, they can help players avoid heat related illness and injuries.  It’s something that sports teams of all levels should implement into their training programs if they haven’t done so already, as it’s the only way to get an accurate picture into the atmospheric conditions, making it easy to spot the hidden dangers of heat stress quickly and easily and help athletes avoid potentially bad situations.