Breathless in the city
Can there really be any doubt that street-level pollution in Hong Kong comes almost wholly from the vehicles on our roads? It's definitely not from across the border. But it is frighteningly high, and presents a major threat to public health. Roadside air monitoring stations showed that levels so far this year are much worse than they were in the same period in 2005.
The South China Morning Post reported on Wednesday that the stations in Central, Causeway Bay and Mong Kok recorded the equivalent of 44 days - or 1,066 hours - of 'very high' pollution levels, using the government's outmoded Air Pollution Index (API).
To really understand the true costs of air pollution in Hong Kong, we should be looking at the Hedley Environmental Index. This monitors and publishes in real-time the economic costs of Hong Kong's air pollution in terms of public health impacts and their monetary value.
What most people do not know is that even at 'high' or 'medium' API levels, the pollution is bad enough to affect our health. That's because the API is based on a set of outdated air quality objectives. These have not been revised since 1987 - yet health science has advanced a lot since then and much more is now known about the impact pollution has on people. Clearly, then, these objectives cannot protect our health; air quality that meets them just isn't good enough. Worse, not meeting these objectives presents an enormous health hazard.
Almost on a daily basis, roadside air pollution levels are 'medium' to 'high', and quite regularly reach 'very high'. We have just three roadside monitoring stations - in Central, Causeway Bay and Mong Kok - so people naturally assume these must be the most polluted areas. This is not necessarily true; we just happen to measure pollution levels there. They were chosen because they are areas with a high density of population and traffic, yet there are other, just as busy, places where the pollution may be even worse. We don't know, because we are not measuring the levels.
The bottom line is that pollution from vehicles poses a severe health threat to a very large number of citizens. Just how many people? Well, consider all the streets where the 'canyon effect' traps pollution between buildings. Now think of all the people who live in low-rise, older buildings or on the lower floors of high-rises, as well as those who attend schools and clinics in some of the most densely populated areas of town. Then there are the people who work in such areas, particularly those in shops and cafes that open onto busy streets. And, let's not forget drivers, street vendors, street cleaners, postmen and police officers on the beat. The number of people exposed to very high levels of roadside air pollution for a significant time every day must be enormous, perhaps in the millions.