In the last two decades, 13% of the incarcerated people who died in Texas prisons in the hotter months of the year were affected by heat stress that could have been alleviated by air-conditioning, says a groundbreaking new study.

Published recently in the journal JAMA Network Open, the new study found that a “a 1° increase above 85°F in prisons without air conditioning was associated with a 0.7% increase in the risk of daily mortality.” A single extreme heat day “was associated with a 15.1% increase in mortality in prison facilities without AC.”

The study found a clear correlation between heat stress deaths and the absence of air conditioning: “An average of 14 deaths per year between 2001 to 2019 were associated with heat in Texas prisons without AC, versus no deaths associated with heat in prisons with AC.”

The problem of preventable heat-related deaths is common in the Texas corrections system. Two-thirds of the state’s nearly 100 prisons lack air conditioning and “regularly reach 110°F” in the summer months, according to a July, 2022, study by the Texas A&M Hazard Reduction and Recovery Center.

And yet, these potentially lethal conditions are not against the law. “Texas regulates the internal temperature of jails to stay between 65 and 85°F degrees, but these same standards do not apply to state and private prisons,” according to the JAMA report.

“There is life-saving potential if the Texas Department of Criminal Justice applies a similar temperature regulation policy to its prison facilities as it does to its jail facilities.”

Research lead and Brown University doctoral student Julianne Skarha told Grist she believes the JAMA study has relevance far beyond Texas. “We know there are many states in the U.S., especially in the South, that don’t have AC in the majority of their prisons,” Skarha said. “There’s no reason to assume that it’s not a similar story there.”