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Research: Sports venues can be hotter than weather apps show

ASU studies show that weather apps can lowball temperatures when it's hot out.
June 30, 2022

ASU studies highlight importance of being vigilant about high temperatures

Recent research by Arizona State University professors highlights the heat dangers in the Valley of the Sun and emphasizes the need for residents to acclimate and check temperatures.

Floris Wardenaar, an assistant professor in the College of Health Solutions and one of the team members, had two studies published recently on dealing with high temperatures.

Both studies involved measuring the temperature of athletic venues on the ASU campus.

One study, published in the journal Environmental Research Letters by a team of ASU researchers, measured the temperature of five venues during five days in June and five days in August. They then compared the measurements to the readings posted by regional weather stations. The team found that on-field measurements averaged about 5 degrees higher than the temperatures posted by the weather stations – about 83 degrees at the sites compared with 78 degrees at the stations. 

The stations were in the Arizona Meteorological Network, which includes four sites in greater Phoenix.

Wardenaar said that the basic weather app that people consult on their smartphones draws data from these stations. So while your app might give you a temperature reading before you go out to play sports, the actual temperature at the venue could be higher. 

“We wanted to know if the microclimate of the surface impacts the heat that people experience in those different environments,” he said.

“One of the things we found out is that there is a difference between the microclimate and what we find on the AZ Met system in the area, which has to do with the location of the systems, where they are placed, but also maybe the height of where the measurement is taken.

“We found that there is a substantial difference between the information that comes from the station that goes to your app. Everyone with a phone has the app that’s pulling data from local stations.”

“The actual heat stress on the ground is much higher,” said Wardenaar, who did the research with Jennifer Vanos, an assistant professor in the School of Sustainability, Matei Georgescu and David Hondula, both associate professors in the School of Geographical Sciences and Urban Planning, and Haven Guyer, a master’s degree student.

The surfaces measured were: the rubber track at Sun Angel Stadium, the artificial turf field north of Sun Devil Stadium, the clay surface of the baseball field at Phoenix Municipal Stadium, a natural grass surface at Phoenix Municipal and the asphalt courts at Whiteman Tennis Complex. Little temperature difference was found among the surfaces, which were measured using a Kestrel 5400 Heat Stress Tracker.

Wardenaar said that the study did not include rock surfaces.

“A lot of the hiking that takes place is on rocky surfaces, and rock builds up a lot of heat and radiation,” he said.

“People should be mindful that when the app says it’s a certain temperature, it is likely to be a little warmer when you are on the actual field. And when the humidity increases, it will make it worse."

Effects on performance

Wardenaar said the other study addressed whether the surface temperatures impacted actual playing performance.

That research paper, published in the International Journal of Sports Science & Coaching, measured the impact of different playing surfaces on Sun Devil football players when it was around 91 degrees outside. The three surfaces were the indoor practice facility, natural grass outdoors and the “HydroChill” artificial turf field outdoors.

Wardenaar said the research team, which included Joe Connolly, the Sun Devil Athletics head coach for football sports performance, was interested in differences between the surfaces because the “HydroChill” turf is not made of rubber crumb from recycled tires, like typical turf, but of coconut, which is meant to hold moisture better and thus be cooler.

The surface comparisons were not same-day because the players worked out on different venues on different days. But they found that the temperature was much higher on the turf than on the natural grass.

The surface temperature of the turf was about 152 degrees on a morning when the air temperature was 95.

The surface temperature of the natural grass was about 91 degrees on a day when the air temperature was about 90.

The surface and air temperatures in the indoor facility were around 80 degrees, but the humidity was much higher – 28% compared with 15% or less for the outdoor sites.

While the “HydroChill” turf got quite hot, typical artificial turf may be much worse, Wardenaare said.

“We see a lot of artificial turf playing surfaces for kids, and that’s probably not the best to be around in summer when it’s really hot,” he added.

When comparing the impact on the football players’ physiological responses from the different surfaces, the researchers found little difference. That’s probably because the players, who start working out in the early spring, had become acclimated to the heat.

“If I translate that to normal people, that says to me that when the weather is warming up, before now, people should try to go outside, because it will help them to acclimate,” Wardenaar said.

“The more you go outside at the start of hot weather, like in March, the better you’ll deal when it’s really hot.”

Unfortunately, he said, most people do the opposite: “When it starts getting warm, they go inside.”

Top image courtesy iStock

Mary Beth Faller

Reporter , ASU News


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Humanity on wheels

June 30, 2022

City of Tempe, ASU partner on 'Jenny’s Trailer' to provide space for homeless individuals to cool off during summer

As soon as the white Chevy pickup truck hauling a 20-foot yellow travel trailer wound its way into the parking lot of the city of Tempe’s Daley Park, Kennan Parrish knew he was among friends.

He could cool off, have a drink of water, watch television, charge up his smartphone and experience a touch of humanity. The latter is important to Parrish, who has been homeless for the last two months after a series of unfortunate circumstances, including the death of his longtime partner and getting evicted from his apartment.

“It’s amazing what I’ve learned about being on the street these past two months, but if I could survive my mother-in-law for 34 years, I can get through this,” said the 56-year-old on June 22, a day that featured triple-digit heat throughout the Valley. “Even though we’re homeless, we still have a heart and we still have something to offer. ... This trailer is phenomenal.”

Parrish is referring to Jenny’s Trailer, a new mobile cooling center that is a welcome respite and serves as a place of shelter from the brutal summer heat. It is a collaborative project in partnership with Tempe’s Homeless Outreach Prevention Effort (HOPE) and Arizona State University’s Healthy Urban Environments initiative, which designed the sustainable, solar-paneled trailer.

Staffed by the city of Tempe, the HOPE team travels around city parks and other locations each Wednesday for two hours, offering a safe, comfortable place to cool off and receive cold bottled water. The trailer is a place for people to connect to housing and social services offered by Tempe. It also offers the “milk of human coolness” to a segment of people who are often ignored by society.

“Many of us go about our daily lives and we forget about our unsheltered population, right?” said Geno Morris, who has been a homeless outreach specialist for Tempe for three years and has more than a decade of experience working with homeless individuals. “As we go about our lives, we get in and out of our air-conditioned cars and we go home to our air conditioning. We think, ‘Oh man, it’s so hot,’ and we forget about the individuals who don’t have a home and don’t have a place to cool off.”

In addition to Jenny’s Trailer, Tempe has seven city and community heat relief locations, as well as two sites available on excessive-heat-warning days. The centers offer a place for all residents in need, sheltered and unsheltered, to cool off, hydrate and access services as needed.  

Morris said Jenny’s Trailer allows him to develop a special bond with individuals and families experiencing homelessness, who aren’t so quick to trust. During the June 22 visit at Daley Park, some went inside to cool off while others approached slowly. A few grabbed a bottle of water from an ice chest outside the door but never ventured inside.

Parrish said being homeless trains you to sleep with one eye open and to be wary of others until you know their true intent.

“You don’t know who you’re dealing with on the street or what their motives are,” said Parrish, who has already witnessed several overdoses and suicides and has experienced theft. “When I step inside and talk with that gentleman (Morris), I feel like I’m talking to an old friend. ‘What’s going on?’ ‘How’s your day going?’ That means a lot, especially to people who have no one.”

Luckily for Jamie Brenzo, she has someone — her husband Noah. She said they are saving money so that he can test for his Department of Transportation card, something the city is helping him obtain. However, until he is back working full time, they remain homeless.

Brenzo, who hails from Nebraska, was one of about a dozen people in Daley Park who cooled down inside Jenny’s Trailer. Before entering, she grabbed a few extra bottles of water to stay hydrated.

“From opening the door to walking inside the trailer, you can feel the air coming off,” she said, closing her eyes, allowing the breeze to hit her face. “The fact that I can go in, charge my phone and watch a movie is pretty amazing.”

Jenny’s Trailer was named for ASU alumna Jenny Norton, a community advocate for those who are homeless. She funded the project in 2021 with a generous $15,000 donation. According to former Tempe councilmember Lauren Kuby, Norton was inspired to support the mobile cooling center by fond childhood memories of growing up in a South Phoenix trailer park. Schoolmates would often gather at “Jenny’s trailer” to enjoy the park’s common area and pool.

“Jenny Norton is not only a philanthropist but an activist, a humanitarian, and she’s a civil rights pioneer in our state and city, and a former representative,” said Kuby, who is a program manager for ASU’s Stardust Center for Affordable Homes and the Family in the Global Institute of Sustainability and Innovation. “Jenny was also the first person to own an electric car in the state of Arizona, way back in the 1970s.”

Because of Norton’s affinity for sustainability, something she knew she shared with ASU, Norton wanted the university to get on board. That’s when she enlisted the help of ASU’s Healthy Urban EnvironmentsHealthy Urban Environments is a collaborative initiative that combines the power of Arizona State University’s entrepreneurship, research and innovation infrastructure with partnership, support and collaboration from Maricopa County and its communities. initiative, which has partnered with the cities of Phoenix and Tempe on a number of projects to combat urban heat, including finding materials to cool streets, pavement and bus shelters.

Last September, Healthy Urban Environments recruited Engineering Projects in Community Service (EPICS) — a team of students who solve engineering-based problems for charities, schools and other not-for-profit organizations — on the interior design elements for the trailer.

While Parrish is thankful that Jenny’s Trailer will continue to make its weekly runs, he’s hoping that he doesn’t have to see it again anytime soon. Tempe is working to find him permanent housing.

“This little trailer’s going to save a lot of lives,” he said. “And that’s so important, because everybody matters.”

Top photo: Raymond Edmonds and Jamie Brunzo leave Jenny’s Trailer on June 22 at Daley Park. The trailer was designed in part by ASU’s Fulton Schools of Engineering and receives assistance from the Global Institute of Sustainability and Innovation and its Healthy Urban Environments initiative. Photo by Charlie Leight/ASU News