The latest coal boiler manufacturer is announcing it will stop making them, after nearly four decades in business.

The US company is making the switch due to a decrease in coal usage.

According to the company’s CEO, Bob Williams, the company is planning to sell its coal boiler to the Chinese government, and has already sold the last of its stock.

The company said it will keep producing its product until the Chinese state government stops using coal and coal-fired power plants.

In its statement announcing the switch, the coal boiler maker noted that coal use is expected to increase as coal mining in China ramps up.

The decision comes amid mounting public concern about air pollution in China.

The country produces roughly half the world’s coal, and coal use has surged in recent years, fueled by rising domestic consumption of energy from shale gas and natural gas.