QIAN'AN, CHINA - An overloaded coal truck rumbles down from the steel factory and hits a bump, sending chunks of its black cargo skittering and click-clicking along the asphalt. Waiting by the roadside, a farmer swaddled in thick, cotton-padded winter clothing scrambles into onrushing traffic to pick up the pieces.
Four hours a day, four days a week, the villager, whose surname is Shen, comes to a spot near her home where a never-ending procession of coal trucks runs into uneven pavement. A thousand little bumps in the road keep Shen and her husband from freezing in winter.
"If I don't come out here, I stay cold," Shen says as she drops a few more recovered chunks into a sooty burlap sack. In one winter, Shen says, she could burn more than 2 tons of coal, worth more than 1,800 yuan ($260).
Across vast swaths of northern China's countryside, residents go to great lengths to burn untreated coal in home stoves despite government efforts to ban the practice and introduce cleaner — but costlier — types of coal or electrical heating.
That dependence represents one of many challenges facing Beijing as it tries to curb the choking smog that's become a flashpoint for public discontent with the ruling Communist Party.
Experts say coal-fired power plants and steel and cement mills are the main contributors to year-round smog, but household coal-burning in rural areas is a major cause of the spike in pollution during winter, when thick, gray soup-like clouds of dust smother Chinese cities, often forcing highways and airports to close.
Middle-class Chinese have complained vociferously as smog blanketed Beijing over the New Year period. A picture of a high-speed train stained a deep brown after passing through smoggy regions went viral on social media, as did a blog post by a Beijing banker who railed against government corruption and propaganda and pleaded with officials to take action for the sake of their children.
In June, a team of researchers from Princeton, the University of California, Berkeley, and Peking and Tsinghua universities in Beijing published a study that found that household coal use in winter contributed more small and deadly air particles than industrial sources, some of which are outfitted with carbon-capture technologies.
Authorities in Hebei province, which surrounds Beijing, announced in September that they would ban household coal-burning in nearly 4,000 villages near the capital by late 2017, according to state media. Last week, the official Xinhua News Agency quoted a Beijing official saying coal-burning furnaces for heating have now been completely removed from the city's urban districts.
But in rural Qian'an, 220 kilometers (140 miles) from Beijing, in Hebei, China's largest steelmaking region, the riverside road where Shen scavenges for coal is a reminder of the challenges. Up the road is a sprawling factory owned by the Shougang Group, one of China's largest steelmakers _ and polluters.
The other direction opens up into the poplar-lined countryside, where elderly and poor residents burn coal in shallow underground hearths. The government is encouraging them to use cleaner coal briquettes that burn at lower temperatures, but villagers dismiss those as hard to light and lacking in heat.
While residents in poor parts of Beijing get subsidies for using cleaner-burning coal or switching to electricity, such incentives are unheard-of in some other parts of the country.
"We ordinary people are comparatively poor," says Yao Junhua, a 61-year old farmer who lives in a village of single-story homes separated by half-built brick walls and stacks of dried cornstalks. "We want to buy a few pieces of good coal, save some money. We don't want to spend money on coal we can't light."
Coal-burning has been blamed for the tiny, toxic PM2.5 particles that caused an estimated 366,000 premature deaths in China in 2013, according to an August study by Wang Shuxiao, an environmental expert at Tsinghua University.
Wang said cleaner coal would theoretically emit 50 to 80 percent fewer particles than untreated coal, but the process of switching is slow. She said it's taken Beijing, the prosperous capital, close to two decades to phase out more polluting heating methods.
"The switch is happening. It's just not happening as fast as we want," Wang said.
The government has sought to clamp down on the market. At the Guo Zhuang coal shop in Qian'an, a large yard was empty except a few small piles of coal half-covered by tarps.
Market supply has been meager and prices have risen since authorities cracked down on the sale of coal for private use in recent months, said a worker surnamed Lu who spoke only after making sure that visitors were not investigators from the environmental protection bureau.
"Look around — we don't have much and it's not because we are selling it all,'' she said.
On a nearby wall was an October government notice forbidding "unauthorized" coal sales, but coal still made its way to homes. As she spoke, Lu's brother-in-law filled a small truckload and drove off to the home of a relative Lu said was bedridden and needed heat.
Some villagers are unconvinced that the coal they burn contributes much to the country's air-quality problems.
"Look at our chimney. That little bit of smoke is called pollution?" says Yao, the villager. "Look at the steel mill. How much coal does it burn a day? The 400 households in our little village, how much coal do we burn?''
The Associated Press was unable to reach Shougang Group using phone numbers listed on its website and email.
On the country road outside the steel mill, its smokestacks rising out of the haze, Shen the coal scavenger says her 65-year-old husband did construction work but is now too old. Her daughter recently married and moved to a city but can't help them because she is saving for a house and a car.
Scavenging coal keeps them warm, and sometimes they have enough left over to sell, Shen says as another truck hits a bump and drops pieces of coal.
"These things are precious," she says. Then she scurries back into traffic.