Pollution makes Hong Kong look like an old photograph

China has a huge pollution problem. It's getting so bad that the problems are not confined to China itself anymore.

This is Hong Kong, on an average day. Compare it with the ubiquitous pictures of Hong Kong's famous skyline, against a dazzling blue sky - haven't seen a day like that in a looong time. On a bad day you can hardly see across the harbour. There's one advantage, though: nowadays you don't need Photoshop to get that nostalgic 'sepia' effect at sunset...