BEIJING -- China has fulfilled its pledge to ensure better air quality during the Olympics and Paralympics period in Beijing and the co-host city of Zhangjiakou, an official said Wednesday.

Liu Youbin, a spokesperson of the Ministry of Ecology and Environment, told a press conference that air quality in Beijing and Zhangjiakou, where the Winter Games took place, met standards every day during the Beijing Winter Olympics and Paralympics.

Both Beijing and Zhangjiakou saw their readings on the air-pollution index fall, with the average concentration of PM2.5 in these two areas standing at 36 micrograms per cubic meter and 22 micrograms per cubic meter, down 56.1 percent and 50 percent year on year, respectively, Liu said.

The ministry's trans-regional campaigns to treat air pollution in Beijing and nearby areas have made notable progress, as the average concentration of PM2.5 in the Beijing-Tianjin-Hebei region and neighboring regions was 52 micrograms per cubic meter, down 20 percent year on year. Days with significant air pollution in these areas dropped over 90 percent from one year earlier.