BEIJING, Dec. 24 (Xinhua) -- About 5.6 percent of villages in north China's 28 cities had reported short natural gas supply for winter heating, an official inspection found.

Inspection teams into these cities in or near the Beijing-Tianjin-Hebei region found that 426,000 households in 1,208 villages had faced natural gas shortage after their homes were heated with gas instead of coal, the Ministry of Environmental Protection (MEP) said in an online statement.

Officials took measures such as increasing gas supply or temporarily heating the homes with coal to ensure all the residents in these villages enjoy a warm winter as of Wednesday night.

To make the air cleaner, China has been replacing coal-fired boilers with natural gas and electricity-powered boilers in the smog-plagued northern region.

Over 4.7 million households in 21,516 villages in the inspected region have completed the coal-to-gas or coal-to-electricity conversion, 3.94 million of which finished the switch this year, according to the MEP.

China is intensifying efforts to fight pollution and environmental degradation after decades of growth left the country saddled with problems such as smog and contaminated soil.

Tackling pollution has also been listed as one of "the three tough battles" that China aims to win in the next three years, according to the Central Economic Work Conference, which concluded earlier this month.

Thanks to the initiatives, China's northern region has been enjoying cleaner air this winter. The density of hazardous fine particle matter PM2.5 in the Beijing-Tianjin-Hebei region stood at 60 micrograms per cubic meter in November, 41.2 percent lower than the same period last year, previous data showed.