IN many of the world's great cities, pollution is an unpleasant fact of life. Tragically it is also a fact of death. Statistics on the rates of mortality it causes in crowded urban areas can be hard to pin down. However, it stands the reason that anyone with an existing condition such as asthma, is in immediate danger. But the poisons carried by unseen particulates belched from engine exhausts, power stations and home fires have a more insidious effect on previously healthy individuals. Delhi is currently caught is a smog which has reduced visibility to just meters. The authorities blame the burning off of stubble in farms outside the capital. But though such activity is clearly contributing to these record levels of pollution, the underlying causes are far wider spread. According to the latest World Air Quality Report, India enjoys the dubious distinction of having 22 of the world's top 30 most polluted cities. Besides the appalling diminution of quality of life for citizens, there can be do doubt that millions are suffering long-term health problems because of the runaway accumulation of noxious gases in the atmosphere. The authorities are struggling to cope. Introducing restrictions based on odd or even vehicle registration numbers is a classic step which has proved of dubious worth where it has been tried elsewhere. Not the least of the challenges for Delhi's police force, is that they or traffic cameras often cannot actually see a number plate in the smog. In Beijing, in advance of the 2008 Olympics, the Chinese government came up with a radical way of tackling the problem; they closed down a large number of local coal-fired power stations for the duration of the Games. But this of course was only a temporary fix. Genuine, lasting solutions are necessary, not least in India. London was once famous for its smogs, which in the late 1950s were every bit as bad as in Delhi this week. The British brought smogs to an end by banning household fires and shutting down big power stations, such as the iconic Battersea, in the heart of the city. But there were also other important steps taken in the UK and Europe. Not the least of these was to introduce and vigorously enforce legislation that forced vehicles with inefficient and badly maintained engines off the roads. Relatively cheap Tuk Tuks may make wonderful little taxis and delivery vehicles but with their two stroke engines, they are among the least environmentally friendly modes of transport. In 1998 Delhi city fathers forced the introduction of LPG as a fuel but this is still not always used. Moreover, undisciplined Tuk Tuk drivers frequently cause the huge traffic jams which have tens of thousands of motor vehicles stranded with idling engines. There are no easy solutions to the unacceptable levels of pollution, particularly in Asia; Pakistan and Bangladesh also have cities draped in noxious clouds. And even when smogs have been banished, there will still be dangerous levels of unseen pollution from automotive engines and home boilers and inefficient power stations. But one key step to cutting smog is actually the simplest; it is to actually enforce all the very sensible rules and regulations that have actually already been passed, without fear or favor.