Hebei province released the ranking of ten major counties' monthly air quality for the first time on Tuesday.
The move came after the province listed eight new counties with huge potential for development in February as counties that are directly under the administration of the provincial government.
The new counties include Qian'an, Ningjin, Zhuozhou, Huailai, Pingquan, Renqiu, Jingxian, Weixian, Dingzhou and Xinji.
Pingquan county, which once belonged to Chengde city, tops the list with the best air quality in April among the ten, followed by Huailai.
According to the provincial environmental watchdog, the air quality comprehensive index of Pingquan is 5.01 in April, 22.20 percent down from the previous month.
The county with the worst air quality is Zhuozhou, with its index in April reaching 17.15, 89.29 percent up from March.
The index of Dingzhou and Xinji are 7.66 and 8.11, respectively.
Government officials of the two counties were summoned to the Hebei Environmental Protection Department in March to review their pollution problems and figure out how to improve the air quality.
Among all 143 counties monitored in the province, Chongli in Zhangjiakou has the best air quality with its index in April being 2.89.
The county will hold winter sports events if the bid to host 2022 Winter Olympics is successful.
