Low-grade coal is cheaper, but poses pollution challenge

Ministry inspections find practices in rural areas haven't been monitored

The recurring gray smog in Beijing is a symbol of the thorny side of the country's modernization. The challenge is how to alter the use of the inferior coal that's responsible for much of it.

Around 200 million residents in rural China, mostly in the northern parts of the country, use coal for household heating during the winter. To save money, many of them tend to use inferior types, Economic Daily reported.