Kevin Frayer’s photographs of illegal Chinese steel factories look like postcards from the dawn of the Industrial Revolution. Thick smoke spews out of tall stacks, steam rises from vast pits, and molten steel flows across the ground like lava. All around, men toil without even basic protective gear. “It was like stepping back in time,” says Frayer, who spent four days at two steel factories in Inner Mongolia in early November. “The way of working seemed unchanged and unaffected by technology.”

China produces more than 800 million tons of crude steel each year, but its vast industry faces radical change as the country curbs carbon emissions. The government announced in January that it will cut production capacity by up to 150 million tons by 2020, and curb coal production by 500 million tons.

Implementing that may prove difficult. Many mills—like those Frayer photographed in Inner Mongolia—ignore orders to shut down. Some operators simply pay a small fine, and local inspectors look the other way. “The sheer size of the country and scale of the industry means it will take time and there are many obstacles,” Frayer says.

Photographing the factories wasn't any easier. Frayer spent a few hours each day at two mills, braving searing temperatures, choking pollution, and the constant threat of being hit by the embers and debris constantly emitted by the massive furnaces. “It’s very hard to work close to them for more than a few seconds,” Frayer says. “One can be easily burned.” The dangers come through in Frayer’s dramatic photographs, which reveal something very close to hell on earth.