when you were told this people were just looking at the greenhouse gases which affected the upper atmosphere, this was down to the carbon monoxide emmisions given off when burning pertol.

What has happended since is there have been a proliferation of diesel engined cars. Diesel emmisions dont give off the carbon monoxide gases but do give off Nitrous Oxide. Nitrous Oxide in general does not affect the greenhouse syndrome so they were thought to be less pollutung than petrol. However Nitrous Oxide is far more dangerous to humans as it hangs around at low level. It is more cancerous than Carbon Monoxide and can cause severe lung problems in young children and the elderly especially. It is probably the main reason for poor air quality in towns and cities. DPF's were fitted to diesel vehicles but they do not combat the Nitrous Oxide pollution.

So if you dont want to cuase lung problems for your children and grand children or even yourself in later life dont use diesel engines.

The UK and other governments have just switched onto this fact, about 10 years too late, and are faffing about again trying to think of ways to get people to move away from diesel. So dont hold your breath that they will do somthing about it soon, or perhaps you should if you live in a city.

What has happenned to have this policy reversed?

Simply its time to shift the goal posts again, this storm in a teacup is just another wheeze to get a few more quid to stave off the country's inevitable bankruptcy.

They set VED on CO2 levels, so increasingly owners of Diesels (they were told to buy because they were good for the environment) are paying too little.

We've seen increasing publicity about how harmful Diesels are, its a softening up process to ease the inevitable VED, and possible fuel tax, hikes on Diesel cars and fuels.

Basically they want your money in ever increasing amounts, no change there then, there's probably a few dictators and current allies...as Saddam, Gaddafi and others who's status changed when it suited...who need bribing with foreign aid/weapons/intervention.

You'd think any foreign leader, sitting on oil or something else the west wants to take, would have got the gist of things by now and forsee their own fate should they cosy up to the US/EU.