HOUSTON (AP) — Amid a summer heat wave that has pushed temperatures in some Texas prisons without air conditioning to 100 degrees Fahrenheit (38 Celsius), many inmates fear dying or falling gravely ill from the hot weather and believe actions taken by officials to mitigate the dangerous conditions continue to fall short, according to a new report.

The report comes as the head of the Texas prison system told lawmakers this week the oppressive working conditions caused by the lack of air conditioning in many of the state’s units is likely contributing to difficulties officials are having in filling 7,000 prison job vacancies.

“Without air-conditioning or regulated temperatures, the system will continue to be under extreme stress and members of the (Texas Department of Criminal Justice) population will remain on the brink of potential health emergencies. This could kill them, but if it doesn’t, it will certainly degrade their health over time,” according to a report released this week by the Texas A&M University Hazard Reduction and Recovery Center and Texas Prisons Community Advocates, an advocacy group for inmates.

Advocates and others have been highly critical of the lack of air conditioning in the Texas prison system, which has 120,000 inmates. Only 30% of Texas prison units are fully air-conditioned.

In 2017, U.S. District Judge Keith Ellison in Houston said the nation’s largest prison system was “deliberately indifferent” to heat risks and subjected inmates to “a substantial risk of serious injury or death.”

Ellison’s comments came as part of a settlement of a lawsuit filed by inmates at one unit.

Texas is one of at least thirteen states in the U.S. that doesn’t have universal air conditioning in state prisons, according to the university’s report.

In the wake of the settlement, the Texas Department of Criminal Justice, or TDCJ, formalized many of the heat mitigation policies it had been following, including providing water and ice, creating respite areas where inmates could go to cool down and allowing inmates to purchase cooling items such as fans or towels.

But the university report called the procedures in place “inefficient and ineffective” as they’re not designed to offer system-wide relief but instead rely on overworked prison employees to offer help on an individual basis to inmates while also suffering through the heat themselves.

As part of the report, 309 Texas inmates were surveyed about their experiences.

“I fainted four times in my cell and no reports were filed and I received no medical attention,” one inmate wrote.

Other inmates described seeing prisoners pass out from exhaustion as they worked outside in the heat and not being allowed to go to respite areas where they could cool down.

“This issue is only going to continue to worse with increasing annual temperatures,” Carlee Purdum, a Texas A&M research professor who helped write the report, told the Texas House Appropriations Committee on Tuesday.

Earlier in the meeting, Bryan Collier, executive director of the Texas Department of Criminal Justice, said in the last 10 days, the average temperature inside the housing areas at non-air-conditioned prisons was 91.4 degrees Fahrenheit (33 Celsius), with five units having average temperatures over 100 degrees Fahrenheit (38 Celsius).

So far this year, six inmates and 11 employees have been treated for heat related illnesses. There have been no heat-related deaths in Texas prisons since 2012, Collier said. There were 17 deaths from 2000 to 2012, with 10 of those deaths just in 2011, when Texas experienced a record heat wave.

But Collier told lawmakers the prison system has “a wide array of things we do to manage heat,” including providing extra ice and water in housing areas and training staff to monitor temperatures and shut down activities when temperatures get too high.

Collier told lawmakers on Tuesday it would cost about $1.1 billion to install air conditioning in all of the state’s prison units.

A bill that would have required TDCJ to install air conditioning failed to pass during last year’s legislative session.

State Rep. Carl Sherman, D-DeSoto said air conditioning can be provided in Texas prisons “if we have the desire to do this.”

“This is about being politically humane,” Sherman said.