Hardly a day goes by without us being reminded of global warming, green issues, pollution, saving the planet and so on. The trouble is that some of the issues have been confused. Not very long ago, we put lead in petrol and that was not a Good Thing. I can remember when every industrial city in the UK would have periods when smoke from chimneys could not escape because of the weather. Thousands died every year because of air pollution, but not much attention was paid until London suffered smog in the early 1950s and the death rate through respiratory illness shot up.

Ella Fitgerald could sing, A Foggy Day In Old London Town and be believed. No Sherlock Holmes movie could do without the fog. It was once a feature of the place, but has not been for half a century.

The Clean Air Act was passed in parliament and things got better. In the 1960s, it was proposed to clean St Paul's Cathedral of all its encrusted soot and, of course, there were those who protested. They argued that St Paul's had acquired the shite honestly, being in an industrial city. The soot was part of the history of the building though Sir Christopher Wren probably did not have soot in mind when he designed the building.

There are cities where smog is a major problem and the motor car is a contributory factor. I believe that Los Angeles is one, Athens is another. When the British parliament introduced the Clean Air Act, the main problem was the burning of coal, but there were alternative energy sources and coal fired power stations could be sited away from cities. When it comes to the motor car, we do not have a viable alternative to oil.

Toyota and Honda have each produced hybrid cars. DaimlerChrysler has been working for years on hydrogen fuel cells and has made enormous progress. Within the last couple of weeks, BMW and Honda have both announced evaluation programmes using hydrogen.

BMW will lease 100 7 series saloons with two fuel tanks, one housing liquid hydrogen, the other petrol. To make hydrogen a liquid, it has to be reduced to minus 253 degrees Celsius and that consumes a lot of energy. Honda is to lease the CFX, which has a fuel cell. It is the second such experiment by Honda, but this time the fuel cell is a Honda product.

Both the BMW Hydrogen 7 and the Honda CFX are claimed to have zero emissions, which is a good thing. A problem is that the hydrogen is obtained from natural gas which, like oil, is a finite resource. There is no shortage of hydrogen, two parts in three of water is hydrogen (you and I are mainly made of water) it is the energy required to separate it which is the sticking point.

Hybrid cars sound okay on the surface, but there are the batteries. Energy is consumed in the making of them and then there is the matter of disposal. Honda guarantees the batteries in its hybrid for ten years and that means a nine year old car is worth half the square root of damn all. When you and I buy an old car, we take a punt. It may blow up next day or serve us for years, we buy in hope. A car with a boot full of batteries which you must replace signals otherwise, it won't go does not do it for me. Cameron Diaz does many things for me, buying her old Prius is not among them.

Pollution has been connected to global warming, but I am not convinced the two are as closely connected as some people claim. Global warming is a fact. In the UK, last winter was the warmest on record. Our recent autumn is the warmest since records began in 1731.

I live on the south coast of England, so the climate is pretty mild. We used to get a fall of snow most winters. It was not what a Canadian would call snow, but it was several inches deep and hung around for a couple of weeks. We have not had more than the odd flurry since 1987, though local vineyards are flourishing.