Air pollution concerns have been troubling local residents of Dexing city in southeast China’s Jiangxi province, after many of them see the photos taken on January 6 in a local school showing the sky turned completely pink. The pictures circulated on Sina Weibo show a view of pinky sky from classroom windows.

The pinky sky is not caused by air pollution but a “natural phenomenon”, say officials from Dexing Environmental Protection Bureau. “There are two factories near where the photos were taken, and one manufactures plastic containers, the other produces sulfuric acid. Neither generates any waste that can cause the sky to turn pink”, local media citing officials reported.

When it comes to the reason behind this phenomenon, an official from the local environmental protection bureau says that the color is the result of thickening clouds in the area on that day. The light travelled through a lot more air than it normally does, and caused the molecules scattered the green, violet and blue lights away from people’s eyes.