BEIJING — Beijing pledged on May 25 to intensify efforts to lower the average density of PM2.5 and cut air pollution this year.

The average annual density of PM2.5, airborne particles smaller than 2.5 microns in diameter, will be about 60 micrograms per cubic meter this year, said Fang Li, head of Beijing Municipal Environment Protection Bureau.

Lowering PM2.5 density is the key to solving the problem, said Fang.

Beijing will continue upgrading its energy structure, decreasing vehicles emission and enhancing environmental protection.

In 2016, Beijing had 198 days with good air quality, an increase of 12 days from 2015. Its average density of PM 2.5 averaged 73 micrograms per cubic meter, down 9.9 percent year on year, still 1.1 times higher than the national limit.