IN reference to Mr Limmer’s letter, Oxford Mail, July 30, I note he fails to respond to my claim that the Department of Transport bases vehicle excise duty on the amount of particulates, that part of the exhaust emissions that pollute the air.

Hence the same excise duty on a diesel being far lower than a similar-sized petrol engine.

Every motor vehicle manufacturer has to prove that the emissions from their vehicles meet ever tighter regulations regarding emissions, these results, along with their means of testing those vehicles are subject to regular and vigorous examination under ISO 9000, the worldwide standard.

Both diesel and petrol engines are cleaner now than they have ever been and they are improving all the time.

However, tobacco smoke contains a vast number of carsiogenics, cancer-causing substances.

There are 7,000 chemicals in tobacco, hundreds of which are toxic, 70 of which are proven carcinogens, cancer-causing.

Among them hydrocarbons, formaldehyde, cadmium, nickel, arsenic, radioactive poldium 210 and tobacco specific nitrosamines.

The tenor of Mr Limmer’s letter suggested that I am a one-time smoker, who now claims the moral high ground because I haven’t regressed.

I have never smoked and never had any desire to do so.

You also claim that you promised yourself that you would never become one of those born-again, non-smoker fanatics, by the same tenor of your letter, you just have.

KEN ROPER, Morton Avenue, Kidlington