China has slashed levels of pollution from its thermal power plants over the past five years and is on track to meet a key emissions goal for 2020, according to a new study.

Researchers from China and the United Kingdom have determined that between 2014 and 2017, China more than halved power plant emissions of sulfur dioxide, nitrogen oxide and particulate matter. The three pollutants all contribute to the formation of smog, which is linked to health problems.

The team of researchers analyzed emissions from thermal power plants that burn coal, oil, natural gas or biomass to produce energy, with a particular focus on coal-fired power plants as these are major contributors to ambient air pollution.

According to the study, which was published in the journal Nature, levels of sulfur dioxide emissions in China fell from 2.21 million metric tons in 2014 to 0.77 million tons in 2017, a reduction of 65 percent.

Levels of nitrogen oxide and particulate matter also fell, by 60 percent and 73 percent, respectively, the study said.

The study suggested that China is on track to meet its target of a 60 percent reduction of pollutants across all power plants by 2020. The researchers used data on emission concentrations collected by China's Continuous Emission Monitoring Systems network, which covers up to 98 percent of Chinese thermal power capacity.

"This is encouraging news for China as well as for other countries wishing to reduce their power emissions," said Mi Zhifu, a climate change economist from University College London who co-authored the study. "Thermal power plants combusting coal, oil, natural gas and biomass are one of the major contributors to global air pollution."

"With coal being the most widely used fuel in China, cutting the number of thermal power plants within a short time frame would be challenging," Mi said. "The results of this research are encouraging in demonstrating that coal can be used in a much cleaner way to generate electricity."

The study was carried out by researchers from UCL and Cambridge University in the United Kingdom, in collaboration with five universities in China, and was supported by the Chinese Academy of Sciences and the Ministry of Ecology and Environment.

Mi said the results demonstrated the technical and economic feasibility of controlling emissions from power plants, which he described as "an important step toward reducing the number of deaths attributable to air pollution".

China set its 2020 emissions target in 2014, when it introduced measures to renovate and upgrade existing coal-fired power stations.