Our students’ safety and wellbeing is our highest priority, and District 211 and the IHSA have guidelines regarding weather conditions that may be hazardous. This last school year, the IHSA adopted a new Play It Safe in the Heat guidelines for determining if conditions are safe for athletes to be compete and what modifications should be made during the athletic activity.
In response the new Play It Safe in the Heat guidelines, the Mid Suburban League (MSL) and District 211 have changed their weather guidelines to mirror those of the IHSA. The MSL will use a WetBulb Globe Temperature (WBGT) at the actual playing surface to obtain the most accurate data to determine if it is safe for athletes to compete. The WBGT is different from a “heat index” or a “feels like temperature”. Some common questions regarding WBGT are answered below.
What is Wet Bulb Globe Temperature?
The WetBulb Globe Temperature (WBGT) is a measure of the heat stress in direct sunlight, which takes into account: temperature, humidity, wind speed, sun angle and cloud cover (solar radiation). This differs from the heat index, which takes into consideration only temperature and humidity and is calculated for shady areas. Military agencies, OSHA and many nations use the WBGT as a guide to managing workload in direct sunlight. (National Weather Service Website)
Why the MSL change from the “heat index” to the “WBGT”?
The Illinois High School Association (IHSA), the governing body of high school athletics in Illinois, recently enacted a new heat guidelines that use the WGBT. In an effort to more closely align with the IHSA, the Mid Suburban League has adopted new heat guidelines. There are several advantages to using a WBGT. First, the WBGT can be taken at a specific location. Using heat index temperatures calculated from positions close to the school, but not at the school or on the actual playing surfaces, does not give as accurate a reading. Playing conditions can vary significantly depending upon the playing surface and its location. Second, the WBGT can be taken inside a venue to gather a heat action temperature reading. Currently we do not have a way to gather a heat index for an indoor location. Additionally, the WBGT uses other weather factors, such as wind and cloud cover, to calculate a more accurate “feels like” temperature. The WBGT is used by OSHA and the United States Military when determining temperature and determining if it is safe to work.
Why are the WBGT action temperatures lower than the heat index numbers?
Because WBGT will account for factors such as wind and cloud cover, the calculated action temperatures are actually lower than the previous heat index temperatures. Therefore, the corresponding action levels have been lowered to account for the change.
Why would a practice or contest be allowed to continue when a “heat index” indicates a potential danger?
Because the WBGT uses additional factors such as cloud cover, wind, and sun angle to calculate their reading, the OSHA has determined the WBGT is a more accurate representation of actual temperature and the effects on an individual. When using the WBGT, it is possible to continue an outdoor activity even when the “heat index” reading is elevated because wind speed and cloud cover will affect the WBGT reading but will have no effect on the “heat index”.
What if there is a conflict between WBGT and “heat index” readings? For example, the “heat index” says it is ok to play but the WBGT says practice should be canceled.
When a WBGT temperature is available, the decision to restrict or cancel practices and games will be based upon the WBGT readings and the restrictions table.
Protocol for Determining the WBGT Temperature
For the purposes of establishing temperature activity restrictions, WBGT readings will be taken on three different surfaces at the school site—grass, turf, and tennis courts. Decisions about play will be made separately for each surface based on that surface’s WBGT reading. If a team is practicing or competing at the school’s off-site facility (ex. golf or cross-country), the WBGT temperature taken on the grass surface at the school will be used to determine temperature activity restrictions at the off-site location.
The athletic trainer will take WBGT readings thirty minutes prior to the start of a game or thirty minutes prior to the start of the day’s activities. Once the initial reading is taken, WBGT readings will be taken at the time intervals designated by the plan until it has been determined the WBGT readings are below the yellow zone.
Minimum restrictions for athletic activity will be established thirty minutes prior to the start of activity. Readings will be recorded in writing and the records will be maintained within the athletics department. Use Table 1 (see below) with an on-site WBGT reading for appropriate exercise modifications during all indoor and outdoor athletic activities.