Watching the wet bulb globe temperatures this week

What they are and how they impact your body and outdoor activities
Published: Aug. 21, 2023 at 7:31 PM CDT
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SPRINGFIELD, Mo. (KY3) - Whenever the temperatures and humidity start to climb in the Ozarks, we tend to look to the heat index or feels like temperatures for the effect on your body.

However, there’s another parameter that meteorologists and other officials use to gauge just how dangerous this high heat and humidity is. The wet bulb globe temperature is an important number that health officials like Michael Lane, Sports Medicine Outreach Manager for Mercy Hospital, watch very carefully.

“It’s a huge statistic,” Lane said. “Our athletic trainers work very closely with other professionals like district administrators and athletic directors to provide this type of information that we see as the gold standard for hot days like today.”

The wet bulb globe temperature (WBGT) is measured differently than the heat index. Unlike the heat index which just takes the temperature and humidity in the shade into account, the WBGT takes the temperature, humidity, wind speed, cloud cover and the sun angle all into consideration and in direct sunlight.

This is more helpful for those that exercise, work, or play outdoors when heat and humidity are in the forecast. Lane says his trainers don’t stop at just taking this measurement with their heat stress trackers once a day.

“A lot of times, we take the number an hour before practice,” Lane said. “That’s so we can give our coaches an idea of what’s the most appropriate plan based on what we’re looking at. Then, we take those numbers every 15 to 30 minutes so their method of practice can be adjusted.”

Lane says their trainers follow the guidance from the Missouri State High School Activities Association to help the many school districts they work with determine what works best for their students.

A number below 82° means it’s safe to go as usual. When the numbers go between 82° and 86.9°, athletes at risk or those more susceptible to heat issues should be monitored closely. MSHSAA guidelines say that WBGT temperatures between 87° and 89.9° should mean outdoor practices limited to 2 hours.

90° to 92° WBGT temperatures force outdoor practice recommendations down to one hour. Anything above 92° should discourage any outdoor practice.

The WBGT may have a lower range of temperatures compared to the heat index. However, Lane and other officials say the higher that number goes, the more difficult it will be for your body to cool down through sweating. That process starts being hampered with that temperature at 82°.

At 92°, your body can’t cool down on its own. Lane said once that number was hit for many districts in the area, the decision about practices were easy to make.

“Districts that saw these numbers either postponed, canceled, or move their practice indoors,” Lane said. “We don’t want to put student-athletes at risk. That’s the biggest thing... What will be the most safe thing to do in this situation? I think our coaches understand that we’re not going to mess with the heat. It’s something that waits for nobody.”

These numbers don’t just apply to student-athletes, though. Anyone with outdoor interests should know that when the WBGT or the heat index gets dangerously high, the safety precautions are all the same. Stay inside if you can. If not, take plenty of frequent breaks inside with air conditioning.

Lane also encourages to stay hydrated and not to skip any meals. Breakfast, lunch, and dinner will provide nutrients to help make sure your body can stay hydrated and cool down. All of these are easy precautions to take until we can shake off this heat wave by the coming weekend.

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