Mask on, mask off?

[The Following is a blog I wrote for New Scientist. Check out the original here]

Is Beijing's air safe to breathe?

Members of the US Olympic team came under fire earlier this week for embarrassing their Chinese hosts... by parading through Beijing airport with anti-smog masks covering their faces from ear to ear.

But with the Games' Opening Ceremonies less than a day away, the question remains whether such precautions are a good idea, or worthy of the apology the team members later made to Chinese officials.

One thing that is clear, however, is that the emergency anti-pollution measures enacted on 20 July - pulling half the cars off Beijing's streets, halting construction, shutting down factories - are having little to no effect on the city's pollution levels.

A frequently-updated chart of the city's Air Pollution Index (API), compiled by researchers at Tsinghua University in Beijing and the University of Rhode Island in the US, has found no correlation between the emergency measures and the air quality. In fact, pollution levels nearly doubled in the first week following the 20th, before subsiding.

The reason, says Kenneth Rahn of the University of Rhode Island, has everything to do with wind, and little to do with local pollution prevention measures.

So long as the winds continue to blow out of the south - where the forest of coal-fired plants that powers Beijing is located - air quality in Beijing will continue to worsen, until northern winds out of Mongolia clear the skies. It's a pattern that repeats itself about every two weeks during the summer, and as the Games are about to begin, Beijing is one week into foul air buildup.

But just how bad are pollution levels in the city right now? It depends on who you ask. Most days the API has remained below 100, the magic safe number, as determined by China's Ministry of Environmental Protection.

Yet each country's measurement of API is a little different, making it hard to say just how foul things really are. BeijingAirblog does a good job of converting Beijing's figures to US and Hong Kong API measurements. It finds that the city's current air pollution would register as moderate in the US and, surprisingly, high in Hong Kong.

Walking through central Beijing on Monday afternoon - early in the current week-long pollution buildup - I found pea-soup skies and a sun that disappeared behind a thick haze at 5:30, nearly two hours before actual sunset.

If I were an athlete, I think I'd make whatever apologies were necessary, but give them through the best mask I could find on any days I didn't see blue skies overhead. Still, I wouldn't be pointing any fingers; I doubt the API of Los Angeles in 1984 was much better than today's Beijing.

Phil