Every morning at 8 a.m., Wang Ruchun in Shijiazhuang, capital of Hebei Province, takes a photograph of the sky from his balcony. It's a routine he has maintained for nearly 10 years. He then checks online for the day's air quality level and pollution index, which he records. With the local air quality steadily improving over the past decade, he decided to change the name of the folder where he keeps his pictures from "Tracking the Haze" to "Tracking the Blue Sky".