The latest statistics on China's 168 key cities show that cities in East China's Zhejiang province accounted for five of the top 20 Chinese cities with the best air quality in August. The five cities were Zhoushan (ranked 3rd), Taizhou (4th), Lishui (6th), Shaoxing (13th), and Ningbo (16th).

In August, PM2.5 densities, small particulate matter that causes smog, for the province's 11 prefecture-level cities fell between 12 and 20 micrograms per cubic meter. The average value, 17, was 15 percent lower than the previous year. With the exception of Huzhou, which maintained the same level of PM2.5 density, all of the cities saw a drop in their PM2.5 densities.

Over the first eight months of this year, cities in Zhejiang accounted for three of the top 20 Chinese cities with the best air quality. The three cities were Lishui (8th), Zhoushan (10th), and Taizhou (16th). Over the same period, PM2.5 densities for the province's 11 prefecture-level cities fell between 18 and 28 micrograms per cubic meter. The average value, 24, was 20 percent lower than the previous year. PM2.5 densities dropped in all 11 cities over the period.