On a crisp Saturday morning last month, men in the black jackets favored by local Chinese officials were going door to door.

They were checking to make sure villagers in Tangshan’s Fengrun district — one of China’s smoggiest spots — had quit burning coal for heat.“We must ensure that ‘not one fire burns, not one wisp of smoke wafts, not one black speck remains,’ ” the Fengrun Economy and Environmental Bureau declared, according to an account of the operation it published.

After knocking on 596 doors, the officials had turned up nearly a ton of unprocessed coal and nine tons of briquettes, and warned residents of the steelmaking hub that burning coal was no longer allowed.

The household checks reflect tensions in China’s northeastern rust belt as the country comes under new global pressure to reduce its carbon emissions.

China is by far the largest greenhouse gas emitter, contributing 27 percent of the world’s output. The country is in the spotlight at the COP26 talks in Glasgow, Scotland, where leaders are discussing how to forestall severe effects of climate change.

China’s President Xi Jinping is not attending the summit in person, but he sent written remarks on Monday that reiterated the country’s carbon emissions will peak before 2030.

For years, China has enacted a range of draconian-sounding measures to tamp down its air pollution, including suspending factory production for weeks on end, allowing cars in Beijing to drive only every other day, and now, raids on household coal stashes.

Yet China’s carbon emissions have continued to grow.

In recent weeks in Tangshan, officials have urged residents to go green by ditching their coal stoves for electric heaters, according to local government announcements. Climate researchers say such measures will have limited impact on emissions, because households use a lot less coal than factories do.

“It’s relatively small fry compared to those major sources of coal consumption like electric power and industry,” said Cecilia Han Springer, a senior researcher at Boston University’s Global China Initiative.

Nearly 60 percent of China’s electricity supply still comes from coal. In guidelines released Oct. 24, China pledged to cut reliance on fossil fuels to less than 20 percent by 2060, but that still leaves a long runway for coal-powered electricity.

Factories also keep finding ways around air-pollution curbs, sometimes by bribing local regulators or falsifying records.

In March, China’s environment minister made a surprise visit to Tangshan, a two-hour drive east of Beijing, after the capital experienced smoggy skies during the Two Sessions, the biggest political event of the year. He found four steelmakers to be faking data to get around air-pollution curbs. The steelmakers were fined, and some of the employees prosecuted.

The stakes will be even higher in February, when Beijing hosts the Winter Olympics. Officials in Tangshan and other cities near the capital have been preparing for months to ensure blue skies.