This is what I have to look like whenever I leave the house this week.

Coming back from three weeks in (mainly) sunny Yunnan province, we were both aware that we’d have to return to the cold of a Beijing winter. Reports from friends suggested that it was getting close to minus 20 at night-time, so warm clothes were packed accordingly. As the plane approached the airport, however, it was the forces of man-made “weather” which turned out to be much more important. The smog had fixed such a dense layer over the city that the plane was forced to re-route to Inner Mongolia, where we slept in a Genghis Khan themed spa hotel and returned more successfully the next day.

After helping out some poor Belgian guy who spoke no English and had missed his connecting flight from the other airport, we took a taxi back through the city. The familiar landmarks were all hidden. We took the same highway I’ve taken back and forth to work for the best part of three years, and I barely recognised where we were until we were almost home.

We spent almost all of the next couple of days indoors, but on those short journeys outdoors it was clear the smog was gradually getting even worse. We’re all used to some very intense pollution here, but this was way beyond usual expectations. To get some idea of how bad, think about this: the WHO safety guideline for PM2.5 particulates is 25, with 50 being “harmful to health”. Levels generally fluctuate between about 100 and 250. In 2010 the US Embassy twitter feed (generally the reliable source for this sort of information) took a reading “beyond index” – their instruments measuring up to 500 – and got into some trouble for labeling this as “crazy bad.”

That was a particularly bad spike, but this week that same twitter feed has been showing “beyond index” constantly. Other measurements have shown the level reaching nearly 900. The tallest building in Beijing, which I work next to, is almost invisible now, and the view from my bus journey home looks like something from an old film about Jack the Ripper, the light from the street lamps being swallowed up in cones of haze. Even with a mask I can smell and taste the stuff, and twenty minutes outside per day has been enough to give me a sore throat.

London and San Fransisco had the same problem before. Many people here still think London is foggy. Both cities put through stringent clean air acts and fought hard to make them work. So far the only action here seems to be this. It’ll be a good couple of decades before it starts to get better, optimistically.

So, why stay here? It’s a good question without a good answer. We have to leave, if possible before the next big wave of smog next winter. I’ve been looking for jobs elsewhere in China and abroad, not easy in this climate but it’s clear that the time has come.