On the afternoon of July 4, as Americans were celebrating the country's independence with elaborate fireworks displays, a prisoner named Joseph Martire passed out in his cell in Texas, amid the excessive heat that has been swamping much of the southern United States in recent days.

In concrete, brick and metal penitentiaries, industrial fans churn warm vapor without really cooling the air. 

And with no air conditioning in most prisons, when outside temperatures exceed 40ºC (104 Fahrenheit), it can feel even hotter inside the cells. 

Some prisoners sabotage the toilets in their cells to make the water overflow and wet the floor, which they then sleep on. Others wet their clothes to try to stay cool, according to convicts, ex-convicts and family members who spoke to AFP. 

In recent weeks, 35-year-old Martire had four heat-related health episodes at Estelle Prison in Huntsville, where he has served 16 years. 

"I just passed out, the medical (staff) refused to see me and I don't know what to do," he told his family by phone. They called the prison administration to seek help.

When other inmates sense that someone has passed out in a nearby cell, they yell to attract a guard's attention, but staff shortages often mean delays, Martire said. 

The stricken inmate is then taken to an administrative area of the jail that does have air conditioning for so-called "respite." Prisoners try to linger as long as possible. 

"I've already had too many issues with my health before from the heat," Martire said. 

Asked what the heat in the cells is like, Amite Dominick of the NGO Advocates for Texas Community Prisons replied: "The fastest way I can explain that is, go sit in your car on a triple-digit day. Bring a blow-dryer with you. Crack your window a little bit." 

- Brick oven -

The Texas Tribune news site reported that at least nine people had died in state prisons in June from heart attacks or other possibly heat-related causes.  

But Amanda Hernandez, spokeswoman for the Texas Department of Criminal Justice (TDCJ), which is in charge of prisons, said the last heat death occurred in 2012. 

In June, the department treated seven cases of people affected "beyond first aid," but there were no fatalities, she said.

The department, which oversees 126,000 prisoners, said that 32 people died in June, from a variety of causes. 

Dominick took issue with that breakdown. 

"The coroner will usually report something like 'cardiac arrest' because heat stroke is highly correlated with cardiac arrest," she said.

"We're seeing the same reports. We're seeing medical evidence for what happens to the body.

"You know, during these types of temperatures, these are heat-related deaths," Dominick added.

Sean Adams, 36, served time in a prison called the Clemens Unit, in the Texas city of Brazoria, but which inmates call "Burns Like Hell."

"It's one of the older units that was made out of, you know, red bricks," Adams said. "And so red bricks are essentially what ovens are made out of."

The prisons agency said inmates have access to ice and water, and can go to air-conditioned rest areas when necessary.

- 'So inhumane' -

Samantha, whose daughter is a 25-year-old inmate at the Lane Murray prison, said three prisoners died there in June from heat-related causes.

"The way that they're treated is so inhumane," she said.

"In the summer months, when you're inside, you see multiple heat-induced seizures every day," said Marci Marie Simmons, a 44-year-old ex-convict and activist. 

She said that in late June, a 36-year-old inmate died in the Estelle prison hours after speaking with her mother and complaining about the heat. 

"If we go and leave a kid or a human being or an animal in a vehicle, we're going to prison. But the state of Texas wants to cook our Texans," said Michelle Lively, whose partner Shawn McMahon, 49, is in Wynne prison.

"And some of them are dying, and they have short, like, stupid drug charges and they have a death sentence because they can't handle the heat," she said.

In leaks to the media, prison workers have also complained about their working conditions, including the heat.

Dominick said legislative efforts to do something about the heat have fallen short, with bills demanding air conditioning in prisons withering in the conservative-majority Texas Senate.

Meanwhile, the state recently spent over $750,000 to purchase several air-cooled units for a large swine breeding operation run partly by inmates, Dominick said.

"And they don't have it for human beings."

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