An ominous black band of air that hung over a city in northern China on Tuesday morning was the result of converging bands of different types of pollutants, state media reported.
The surreal image of the band of grunge snaking around buildings in Zhengzhou, capital of Henan province, caused a flurry of comments online from dismayed residents.
Many suspected it was rebounding air pollution from factories restarting after being idle for for days ahead of last week’s commemorative military parade in Beijing, 600km to the north.
Zhengzhou had the third worst air pollution in the country for the first half of the year, according to the Ministry of Enviromental Protection.
But Tuesday’s phenomenon was due to the change in weather at the onset of autumn, China News Service reported, citing the city’s environmental protection bureau.
Rising air pressure overnight pushed down air pollutants, but after sunrise, as the surface temperature began to rise, pollutants at ground level drifted higher into the sky.