Since the start of the year, China's capital Beijing has been swathed in smog so thick that it is causing health concerns as well as inconvenience. Here's the story unpacked:
Why is this newsworthy?Apart from anything else, the photos are pretty remarkable. Where there were skylines, there are now shadows in a soupy grey haze. And as
pictures from NASA's Terra satellite show, the air pollution appears to have wiped the city clean off the Earth. It is also a big deal because air measurements show that levels of certain substances are way above what is considered safe for humans.

Aerial view of Beijing on January 3

Aerial view of Beijing on January 14