Wang Ruchun, a 78-year-old shutterbug in Shijiazhuang, Hebei province, has taken more than 3,000 photos recording the city's daily air quality since 2014.

"I wanted to record the change of air quality in the city," Wang said, adding that the sky has improved a lot since he began doing so.

A decade ago, his hometown was one of the cities in North China notorious for heavy smog, especially during the cold winter months. The photos taken in the first year prove it.

"Many times I could only see a nearby building in my residential community, and none at a far distance could be found in the haze," Wang said.

With a series of measures in place, days with smog have decreased in the past nine years. In his pictorial record of Shijiazhuang, there were 300 days with blue sky last year, increasing from 290 in 2021 and 105 in 2014.