LOUISVILLE, Ky. — Whether it's time at the pool or a walk in the pack, exposure to warm temperatures can affect the immune system.

Mother-daughter duo Olivia and Lindsey Duncan, who often take the court to play pickleball, said they stay active during the summer months and make sure to take every precaution to be healthy in the heat. 

While extreme heat is likely to increase the risk of heat exhaustion, heart attacks and stroke, there are other risks. Daniel Riggs, assistant professor of medicine at the UofL School of Medicine, was part of a study that found heat can harm the immune system and increase damaging inflammation. 

“We've found that during high-temperature days, people actually had lower levels of B cells," Riggs said. "These are immune cells that help fight infections ... during days (with) higher temperatures, we may be more susceptible to infections.” 

Riggs said research suggests heat exposure likely increases the risk of cardiovascular disease.

“We look at the effects of temperature and markers of inflammation in the immune system," Riggs said. "We found that short-term increases and temperature are related to certain markers of acute inflammation ... so this is a sign that these are related to cardiovascular disease."

Riggs said the elderly, young children, pregnant people, those with chronic health conditions and asthma are all more vulnerable during extreme temperatures.

“If possible, stay in cool, air-conditioned areas (and) wear loose-fitting clothing," Riggs said. "You want to increase your fluid intake; you want to reduce your activity levels." 

According to the National Weather Service, heat is one of the top weather-related causes of death in the U.S.