On a recent sweaty day in the center of a Towson University athletic field, the temperature was 84 degrees.

But, as the sun beat down, Tim Happel, an athletic trainer in MedStar Health’s sports medicine program, held a device that displayed a reading of 91.4 degrees.

It wasn’t malfunctioning. It was tracking something called the wet bulb globe temperature. It’s a mouthful of a measure — and likely unfamiliar even to the athletes being affected by it — but one that gets closer to how it would feel to practice or play a game in the heat.

“It can affect how long practice would be, how many breaks they get, how much water we want them to drink,” said Happel, who normally tends to the athletes at Howard Community College and USA Lacrosse events but was at Towson to help with a medical training exercise.

Although less well known than the heat index that measures only temperature and humidity, officials say, wet bulb globe temperature measures heat stress.

The score takes into account the angle of the sun or cloud cover and wind speed.

Officials say it has become a critical number to protect athletes who work out in sometimes dangerous conditions.

The readings have been rough lately. And there’s no break in sight. The National Weather Service forecast for the next several days calls for temperatures in the 90s — and that’s a measure taken in the shade.

There’s no regulatory requirement to use a wet bulb globe temperature measuring device at athletic events. But a pair of Maryland’s federal lawmakers said this week they want to make another attempt to mandate that college and high school teams have a system ready for the worst conditions.

U.S. Rep. Kweisi Mfume and Sen. Angela Alsobrooks, both Democrats, introduced the Jordan McNair Student Athlete Heat Fatality Prevention Act. Named for the freshman on the University of Maryland football team who collapsed during practice in 2018 due to heatstroke, it would require athletic programs to implement heat illness emergency action plans.

MedStar provides medical assistance to many major sporting events and teams in the region. That includes working with the Orioles and Ravens and several university and high school teams. Officials with the MedStar program start practices and games by taking the wet bulb globe temps, or advise teams on their roster to take them.

Prevention is key on the field or track, or wherever people are in the heat, said Dr. Matt Sedgley, a MedStar sports medicine physician who specializes in running.

There have been 12 heat-related deaths in Maryland this year, outpacing the last three years, according to state data. The deaths include a 6-month-old girl who was locked inside a hot car in Harford County.

The state has already had more than 900 emergency room visits for heat this season, which lasts from April to October. It has been so hot that Baltimore’s Department of Public Works has rejiggered trash and recycling pickup to protect workers. A sanitation worker died last year in the heat.

The hazardous weather has affected sporting events in ways large and small, often behind the scenes.

In late June during an Orioles game against the Tampa Bay Rays at Camden Yards, it was so hot that Major League Baseball’s replay equipment suffered a power failure. Officials used broadcast equipment instead, causing short delays.

The stadium has been providing misting stations to fans who don’t happen to sit in the “splash zone,” tended by the mascot Mr. Splash, who sprays the stands with water.

Sedgley said all MedStar providers use a walkie-talkie-size device from the company Kestrel to measure the wet bulb globe temperature. But he said there are other such devices — and phone apps, too.

The Kestrel has a small, black, bulb-shaped antenna that measures the angle and intensity of the rays of the sun. A coin-size cutout has a fan measuring the wind. And the display shows a number after a few minutes that coordinates with a chart.

Happel’s wet bulb globe temperature reading straddled the yellow and orange sections, indicating an elevated risk but not quite the red-alert level of danger.

According to the National Weather Service, the reading meant “working or exercising in direct sunlight would stress your body after 20 minutes.” That’s when health officials advise athletes to take a break.

Sedgley said the wet bulb globe temperature dictates how the day goes. A few years back, he said, a dangerous reading led to a marathon being canceled. That’s unusual, he said. Typically, a high reading means another water stop and extra medical attendants.

“It doesn’t always make you popular,” he said. “It’s important to keep everyone safe.”

Banner reporter Andy Kostka contributed to this article.