BEIJING, Oct. 22 (Xinhua) -- Beijing plans to cut over 1,800 tonnes of nitric oxide emissions during this year's winter heating season, said Beijing Thermal Group Sunday.

Boilers were upgraded using low nitrogen combustion technology to cut nitric oxide emissions to 15 milligram per cubic meter.

According to Beijing Environmental Protection Bureau, Beijing has eliminated 24,400 tonnes of water per hour (T/h) coal fired boilers in the past four years. Nearly 10,000 T/h gas fired boilers have been upgraded using low nitrogen combustion technology.

Air pollution is more prevalent in north China in winter. While high concentrations of industrial and vehicle emissions are the main culprits, static air and the use of coal for winter heating worsen the situation.