The use of electronic 'E-cigarettes' has tripled over the last two years, with over 2 million Britons now regularly smoking them.
Health charity ASH released figures showing a rise from 700,000 in 2012 to 2.1 million this year.
The group said two thirds of e-cigarette smokers still smoke normal cigarettes, while the remaining third were former smokers.
David Cameron is "minded to go ahead" with introducing plain packaging for cigarettes before next May's general election, Downing St has said.
At a media briefing this afternoon, the Prime Minister's spokesman said:
"The first thing to do is publish the draft regulations. We do have to consult on those in detail, partly to deal with the risk of future charges. Subject to that, we will certainly consider whether that is possible.
"The Prime Minister is minded to go ahead with this, subject to the consultation on detailed regulations," he added.
The tobacco industry has attacked the Government over the decision to pave the way for plain packaging for cigarettes in England.
Several companies said a review by Sir Cyril Chantler saying plain packs could improve public health was flawed.
A spokesman for British American Tobacco, whose brands include Pall Mall and Lucky Strikes, said the idea the plan would improve public health "defies logic".
Japan International Tobacco, the makers of Camel and Silk Cut, also pointed out that David Cameron has said the proposals involved "considerable legal uncertainty".
ITV News Deputy Political Editor Chris Ship has been speaking to Sir Cyril Chantler, the author of a review that concluded that plain cigarette packaging could contribute to a "modest but important reduction" in smoking rates.
Author of smoking study Sir Cyril Chantler tells us #plainpackaging is about "denormalising smoking in society"
The government said it will press ahead with plans to force tobacco firms to sell cigarettes in plain packets which would "very likely" improve public health.
Draft regulations to introduce plain packaging for cigarettes are to be published following the Sir Cyril Chantler review, health minister Jane Ellison said.
Ms Ellison said a short consultation will follow and details of when the changes will take place will be announced shortly which drew cries of "shame" from some MPs.
She said she wanted to move forward as swiftly as possible, explaining: "I am currently minded to proceed with introducing regulations to provide for standardised packaging.
"However, in order to ensure that decision is properly and fully informed I intend to publish the draft regulations so it is crystal clear what is intended".
International scientists conducting the new study looked at data on more than 2.5 million births and almost 250,000 hospital visits for asthma attacks.
Dr Jasper Been, from the University of Edinburgh, said:
Our research shows that smoking bans are an effective way to protect the health of our children.
These findings should help to accelerate the introduction of anti-smoking legislation in areas not currently protected.
Professor Aziz Sheikh, co-director of the university's Centre for Population Health Sciences, said:
This research has demonstrated the very considerable potential that smoke-free legislation offers to reduce pre-term births and childhood asthma attacks.
The many countries that are yet to enforce smoke-free legislation should in the light of these findings reconsider their positions on this important health policy question.
The findings are reported in the latest edition of The Lancet medical journal.
Smoking bans help to reduce premature births and childhood asthma, new research suggests.
A study of data from North America and Europe linked the prohibition of smoking in public places to a 10% fall in premature birth rates.
Hospital attendances for childhood asthma also dropped by the same amount in districts where smoking bans had been introduced.
Anti-smoking laws currently affect less than a sixth of the global population and 40% of children around the world are regularly exposed to second hand smoke, according to the study authors.
More research is needed into the link between smoking and the development of breast cancer in women over 50, US scientists said.
The call comes as a new study from the US National Cancer Institute in Bethesda, Maryland, found that women who smoked after menopause were 19% more likely to develop cancer.
DR Sarah Nyante said her study adds to the growing body of evidence of the association between smoking and increased breast cancer risk.
Previous studies have investigated this relationship, but questions remained regarding the extent to which other breast cancer risk factors, such as alcohol intake, might influence the results.
More work is now needed to understand the mechanisms behind the link between smoking and breast cancer in post-menopausal women.
Scientists in the US have established a new link between increased risk of breast cancer in older women and exposure to tobacco smoke.
The results held true even after accounting for increased alcohol consumption levels, which has already been established as a risk factor.
Former smokers were found to have a 7% higher chance of developing the deadly disease than those who had never smoked.
- US scientists who tracked the progress of 186,000 women aged between 50 and 71 found that those who smoked were 19% more to develop breast cancer than those who had not ever smoked
- Women who previously smoked but had managed to give up were 7% more at risk