Clearing the Smog

Breathing in Beijing is rarely healthy. The smog there is so thick on a daily basis that the tops of all the new skyscrapers are hidden from view.

According to Andreas Wahner, an atmospheric scientist at Germany’s Juelich Research Centre, most of this is due to all the aerosols in the atmosphere. Those are tiny particles that mass together in the air, growing into a sort of fog, reducing visibility.

Beijing isn’t alone

It doesn’t matter if you’re talking about Sao Paolo, Calcutta, or Beijing, the causes of such poor air quality are the same around the world. Wahner says it depends on three main criteria

Traffic, which is a culprit for the obvious reason: burning fossil fuels releases a lot of pollution. Industry is also to blame. It often relies on old technology and machines that release high levels of soot, carbon dioxide and sulphur into the atmosphere.

The third culprit is simply the people living in each city. So many people living in one area, cooking over coal fires or heating and cooling their homes, gives off a lot of pollution.

In 2006, scientists from the Juelich research centre teamed up with specialists from China, Taiwan and Japan to conduct a long-term study of the atmosphere above Beijing. One of the German team’s key contributions has been access to cutting edge technology.

According to atmospheric researcher Andreas Oebel, air quality can be determined by measuring the number of hydroxyl-radicals in the atmosphere. Air is pumped through a chamber and then laser are used to excite molecules to be tested. The energy they produce is turned into light, which is then tested, said Oebel.

“If we get a lot of light, that means there are a lot of radicals, and we know the air is very, very dirty. If we measure a low concentration, then we know that the surrounding atmosphere is relatively free of dangerous substances,” he explained.

The solution

The results of the tests in Beijing weren’t good. The scientists’ recommendation was to drastically reduce the amount of traffic on the city’s roads.

As the Olympics approach, the Chinese government has complied by restricting cars with even and odd-numbered license plates on alternate days, thereby halving the city’s cars on the roads on any given day.

According to Wahner it’s too little, too late. He admits that while there is a reduction in nitrogen oxides when traffic is cut in half, there is also a slight rise in ozone production.

“You’d have to limit traffic much more, to one car in ten, if you want to see ozone levels drop as well,” Wahner said.

Another key recommendation made by the Juelich team was to shut down production at factories in and around Beijing. China's government seems to have taken those suggestions to heart too. Production has been curtailed at several factories in Beijing and outlying areas.

Wahner plans to visit Beijing for the Games later this month to check out the city's air quality which, judging from latest media reports, hasn't really significantly improved despite the measures.