China, in recent times, has faced scepticism over its pledges to wage a "war on pollution" and end the unrestrained burning of coal in the country.

In the northern Chinese province of Shanxi, the country's largest coal-producing region, 27 coal mines were shut down last year. Scores of old coal stoves have been dumped in the trash, removed by government decree in favour of cleaner-burning natural gas furnaces. The province banned the sale, transport and use of most coal by individuals or small businesses in October 2017.

"Defend blue sky and breather together," a poster painted on the brick wall surrounding the waste lot says. The ban was expected to cut coal use by more than two million tonnes, or 90 percent of the city's total consumption, Xinhua has reported.

According to Greenpeace, the pollution in Shanxi, as measured by the concentration of PM 2.5, or particulate matter of size thought especially harmful, dropped 20 percent in the last three months of 2017, after the start of the campaign to remove coal stoves, compared with the same period the year before. In Beijing, the drop was nearly 54 percent for the same period.

However, the demand for coal in the country rose in the last year after undergoing a decline in the previous three years. As many coal stoves were removed before new furnaces were installed, it left tens of thousands of people shivering without heat when winter's first cold snap arrived earlier than normal.

Then, with so many districts switching to natural gas at once, demand for the new source of fuel overwhelmed supplies, sending prices soaring and creating a shortage. The city of Taiyuan, however, made an attempt to replace coal-burning household heating equipment with electric and natural gas heaters, Xinhua reported.

Amidst all this, the benefits of the government's campaign are nonetheless being felt in the comparatively blue skies that have opened up over Beijing and other cities that were a focus of officials' efforts, including in Shanxi's provincial capital, Taiyuan.

In the long run, the impact could be felt globally too, backed up by President Xi Jinping's pledge to put China in the "driving seat in international cooperation to respond to climate change" by reducing emissions.