IN Hong Kong we merely talk about the solutions to pollution. In Beijing, they act. The police in the national capital have found the smoking gun - and, without any Hong Kong style bother with consultation or democratic procedures, they have replaced the safety catch: they have closed Xisi Street to bicycles. To those of us schooled in the notion that motors cause pollution, but pedals do not, this closure of such a major thoroughfare may seem an over-reaction. We might also express astonishment at the lack of respect for tradition. After all, even in these days of socialism with Chinese characteristics, it is hard to believe anyone would dare banish the bicycle, the transport of the proletariat and the symbol of communist progress since 1949. But we would be wrong. It is not that officialdom fails to recognise the rising pollution levels are caused by the 15 per cent a year increase in the number of cars on the road. Right now, it appears there are 1.2 million cars chugging their filthy way through the city. They have made their mark and it is black. However, the argument officials make is that the cars would move faster, and therefore be less polluting, if it were not for the bicycles clogging the roads. There were 6,000 pedal-bikes an hour rolling down Xisi Street in peak periods. Never mind that they did not emit a single hydrocarbon or carbon monoxide molecule between them. Ban bikes and keep the road free for cars. There are lessons here for Hong Kong. Of course, the SAR does not have a problem with bicycles. The problem are the 'bipedals'. It should be clear to all that the real reason for Hong Kong's pollution is pedestrians, especially when they cross the road to the bus stop. If every one of us drove a private car, there would be no need for heavily polluting diesel buses, no diesel taxis or minibuses, and no need to spend money converting them to LPG. The traffic would be heavier, no doubt. If one bus with 70 people aboard were replaced by 70 private cars, they would take up a lot more space on the road. But the chaos at bus stops would be a thing of the past. No longer would traffic be forced to stop whenever a bunch of pavement-pounders wished to cross to the other side. In the longer term, it would make sense to build all the shopping malls and walkways six storeys up too. Pavements could be done away with altogether, making it possible to add at least one and possibly two more lanes to most major urban streets and thus greatly improve the flow of traffic. The lower five floors of every building would eventually become a multi-storey car-park, although we would suggest the Government refrain from hurrying the conversion process by posting a target of, say, 85,000 new spaces a year. The prospect of over-supply could all too easily knock the bottom out of what promises to develop into a lucrative market for speculators. Since there would be no one left on the pavement to breathe the air, it would be pointless to keep pollution monitors at ground level. The Environmental Protection Department would be justified in reverting to its old habit of measuring pollution six storeys above the ground. However, there could be an alternative. It would not necessarily meet with universal approval. It might even be seen as a serious infringement of that very basic human right: the right to own a car. But it might work better than banning pedestrians. What we have in mind would be to ban all private cars - except those of the very, very rich and well-connected and the official cars of civil servants senior enough to qualify for first-class air travel. All new commercial vehicles, whether goods vehicles, buses or taxis, would run on electric motors. And for the flatter areas of the SAR - the Kowloon peninsula, for example, or the Sha Tin valley (where there are already a few bicycle paths) - there could be an official campaign to encourage commuters to start biking to work. YOU never know, Hong Kong's example could start a trend even in Beijing. Instead of banishing the humble push-bike from the capital's broad, but traffic-choked avenues, the authorities might be persuaded to build spacious cycle tracks or allocate a lane of each highway for the exclusive use of cycles, horse-carts and other non-motorised conveyances. Here in Hong Kong - as, no doubt, in Beijing -there would have to be a few exemptions. We have already mentioned the rich and senior civil servants, but the law would, naturally, also not apply to representatives of the Central Government. Foreign consular officials might also try to claim diplomatic immunity. In theory, their local drivers could still be prosecuted for breaking the rules and driving petrol-driven vehicles. But since the police would be on bicycles and would be unable to catch up, no action could be taken against anybody. Which means, you realise, that once the roads are finally clear of traffic, we can once again take the Week Ending Rolls out of mothballs and drive through town with speed and panache. There is nothing like driving a gas-guzzling, large-engined car on an empty road to get you noticed.