Tuesday marks the first anniversary of the introduction of the smoking ban in England.
Thousands of smokers have quit in the past 12 months and nearly two-thirds of landlords now support the ban, according to studies published to mark the milestone.
The Smoking Toolkit Study, unveiled on Tuesday at the UK National Smoking Cessation Conference in Birmingham, found at least 400,000 people have stopped smoking because of the ban. The smokefree legislation could prevent 40,000 people dying over the next decade, it added.
This is the first study in the world to examine in detail the impact on smoking rates solely from smokefree legislation.
Another report published on Tuesday by the Department of Health, reveals 234,060 people have stopped smoking with the help of the NHS Quit Smoking Service since the ban was brought in on July 1, 2007. That is 22% more people than in the previous 12 months.
Professor Robert West, Cancer Research UK's director of tobacco studies, who carried out the Smoking Toolkit Study, said: "These figures show the largest fall in the number of smokers on record.
"The effect has been as large in all social groups, poor as well as rich smokers.
"I never expected such a dramatic impact and of course there are no guarantees that smoking rates will not climb back up again.
"But if the Department of Health can keep up the momentum this has created, there is a realistic prospect of achieving a target of less than 15% of the population smoking within the next 10 years."
The health charity Action on Smoking and Health (Ash) surveyed more than 3,000 people, and found 63% strongly supported the ban on smoking in public places.
