Host city of 2012 Olympic Games asked to learn from China's capital how to enforce pollution-control measures successfully.

The pollution wheel has come full circle, this time to haunt the 2012 London Olympic Games. Environmental concerns now threaten to derail the London 2012 publicity train, reminding one of the run-up to the 2008 Beijing Olympics.

London now has been advised to learn from Beijing's experience to restrict road traffic during the 2012 Games by Frank Kelly, professor and director of the King's College London (KCL) Environmental Research Group. Those who remember what China - especially Beijing - was made to go through during the run-up to the Games would call this a pleasant irony.

London's air quality is one of the worst among major European cities. "There have been no major innovations or advances in the way we regulate traffic emissions. So pollution is no better than it was. In fact, it hasn't improved much since the turn of the century, since 2000," Kelly says.

The heavy traffic is the main source of the city's two major pollutants, particulates and nitrogen dioxide. "If a vehicle is powered by diesel, it will produce a lot more pollution than a petrol-powered" automobile. "And unfortunately, a lot of our transport depends on diesel. All the 7,000 buses and 22,000 taxis, and over half the private cars now are diesel (powered) vehicles".

Pollution has "a lot to do" with the weather, he says. "In fact, the biggest influence on what the air quality is on a particular day is the weather As we can't control the weather, the only other option we can have is to control how much pollution we emit." He suggests London authorities either regulate transport more tightly or insist on the use of very low polluting form of transport.

Peter Brimblecombe says in his book on air pollution, The Big Smoke, that London's dirty air dates back to medieval times, when soft sea coal was burned in homes, breweries and factories. King Edward I tried to ban the high-sulphur fuel in 1306. In 1661, London diarist John Evelyn observed that the city was covered "in such a cloud of sea coal, as if there be a resemblance of hell upon earth".

In 1879, smog hung over London for four months. The Great Smog befell London on Dec 5, 1952, and lasted until Dec 9, and caused or advanced the deaths of thousands of people and became an important impetus to the modern environmental movement. It also prompted the UK parliament to pass the Clean Air Act in 1956, hastened the replacement of coal with natural gas in most homes, and eliminated the city's so-called "pea soup fogs".