BEIJING, March 9 (Xinhua) -- China is heading into the right direction for tackling air pollution, as proved by the improvement of air quality over the past few years, Minister of Environmental Protection Chen Jining said Thursday.

In the past three years, days of good air quality increased in the Beijing-Tianjin-Hebei region, the Yangtze River Delta and the Pearl River Delta, Chen said at a press conference on the sidelines of the annual parliamentary session.

The PM2.5 density in the three regions all dropped by more than 30 percent in 2016 from 2013, he said.

The improvement shows that China is "on the right path" for addressing air pollution, Chen said.

However, the campaign against air pollution cannot be completed in a short period of two or three years, but will need a relatively long time," he added.