AMERICANS James Enstrm and Geoffrey Kabat both hated smoking.That's why they began to look into the effects of secondry smoke inhalation,hoping once and for all their research would help nail this social evil.

They had the full support of their main sponsors, the American Cancer Society and the Tobacco and related Disease Research Program.

After analysing 30 years of American Cancer Society data (1959-1989) they tracked no fewer than 118,000 Californians and was the world's first major long-term investigation into the effects of passive smoking.

But as their study progressed they began to realise something awkward: they weren't going to deliver the results their sponsors wanted.

As they discovered, exposure to second-hand smoke, no matter how intense or prolonged, creates no significantly increased risk of heart disease or lung cancer.

From being heroes of the health lobby they became it's number one villains.

Sponsors dropped them like a hot potato.

The only way to continue research - irony of ironies - was with the backing of the cigarette industry.

Of course, this gave their critics the ammunition they needed not to take their work seriously.

After all it was clearly biased: it had been funded by Big Tobacco.

Will a smoking ban in pub gardens really do any good?

Dave Christian