BEIJING -- Beijing has rolled out a new policy to give subsidies to encourage renovation of boilers to reduce emissions of nitrogen oxides and improve the city's air quality, the Beijing Municipal Environmental Protection Bureau announced on Tuesday.

Renovated boilers with nitrogen oxides emission reduced by at least 50 percent will enjoy a subsidy of one fourth to one third of the total cost of the renovation, said Yan Xiangyang, an official with the bureau.

Beijing published a boiler emission standard for air pollutants in July 2015 mainly to curb the emission of nitrogen oxides.

All the boilers located in the city's six urban districts are expected to reach an emission standard of no more than 80 milligrams per cubic meter by April 2017.

To meet the standard, the 10,000 gas-fired boilers in the city proper, mainly in the six urban districts, will be renovated, according to Yan.

After the renovation, nearly 10,000 tonnes of nitrogen oxide will be eliminated, Yan said.