Improvements in people's health will begin to filter through the population almost as soon as England's smoking ban takes effect today. This is the key implication of a series of studies based on research into existing tobacco bans, as highlighted in Nature last week.

In one study it was found that bar workers in Scotland and Ireland complained of fewer respiratory problems within months of the bans being introduced. And in a study of a six-month temporary smoking ban imposed in 2002 in Helena, Montana, the number of heart attacks fell by 40 per cent compared with other years.

Studies comparing California - which introduced a series of draconian bans in the Nineties - with US states with less severe laws suggest that major improvements in health should quickly become obvious. 'Between 1988 and 2002, rates of lung and bronchial cancer declined four times faster in California than in the rest of the United States,' says Nature

It was found that hospital admissions for heart attacks fell by 11 per cent after bans were imposed in Piedmont in Italy, by 27 per cent in several cities in Colorado and by 39 per cent in Ohio.

The release of these figures comes as England enters the first day of its national smoking ban. Under the restrictions that began at 6am today, which brings England into line with Scotland, Wales and Ireland, it will be illegal to smoke in virtually all enclosed public places and workplaces. Buses, trains and work vehicles used by more than one person will also be affected. Staff smoking rooms will no longer be allowed.

Owners and managers of pubs, clubs and cafes face fines of up to £2,500 if they allow customers to smoke on their premises, while fixed penalties of £50, reduced to £30 if paid in 15 days, will be handed out to individuals caught smoking illegally. Submarines, hospices and prisons will be exempt, however.

At present, about 25 per cent of the adult population of Britain smoke.

The European Commission has found that the country has the highest percentage of Europeans currently trying to quit the habit: 46 per cent are actively trying to stop and even more say they want to give up.

This point was backed by Professor Colin Blakemore, head of the Medical Research Council. 'There is a real desire to give up,' he said. 'More than 70 per cent of smokers say they want to stop.'

However, it is not just smokers who will benefit, scientists stressed last week. Non-smokers who breathe in second-hand smoke currently face increased risks of about 25 per cent of getting lung cancer or heart disease. These rates should improve dramatically once their exposure to the smoke of others is curtailed, though doctors point out that Britain still has 10 million smokers. No matter how deeply the smoking ban affects behaviour, there will still be smokers and there will still be millions of early deaths in coming years.

This last point is stressed by UK epidemiologist Sir Richard Peto. 'There is good and bad news about smoking. The bad news is that the situation is bad, the good news is that it used to be worse.'

In the meantime, the nation's smokers will have to make do with seats on pavements and in beer gardens just as the grim, rainy weather continues to spread across the country. As Will Self puts it on Channel 4 tonight in Memoirs of a Cigarette: 'Global warming cannot come soon enough for smokers outside in the English weather.'