Alison Paul was addicted to smoking for 30 years and made countless attempts to quit.

Key points: It is currently legal to import nicotine to Australia but possession is illegal

It is currently legal to import nicotine to Australia but possession is illegal US study says e-cigarette users more likely to succeed in quitting than non-users

US study says e-cigarette users more likely to succeed in quitting than non-users E-cigarette manufacturers have not submitted product for TGA testing to prove it is safe

It wasn't until she started vaping in 2014 that she found success.

"I would smoke until I couldn't breathe and I would smoke and cough, it felt like my ribs were going to break," she said.

"I felt like I had no way out of that circle. Then I started vaping a few days before my birthday three years ago and I haven't had a cigarette since."

E-cigarettes and vapour devices heat a liquid nicotine juice into an aerosol, which is then inhaled.

Using the nicotine-based products in Australia is illegal because it is classed as a poison by the Therapeutic Goods Administration.

"It's legal to import the nicotine in Australia, but the moment you take possession of it, it becomes illegal," Ms Paul said.

"Basically I'm a criminal for quitting smoking the only way I could."

A study published today in The British Medical Journal has strengthened claims the devices are a useful tool to help smokers quit.

The University of California study looked at whether the increase in the use of e-cigarettes in the USA was associated with a change in smoking cessation rates.

It analysed data from more than 160,000 people and found, of those who had quit, nearly 50 per cent had tried e-cigarettes.

The researchers said the results showed e-cigarette users were more likely than non-users to succeed in quitting.

Should it be legal in Australia?

The study comes as a federal Parliamentary inquiry is examining whether the devices should be legalised in Australia.

Ms Paul was one of more than a hundred people who have written submissions, pleading with the Government to change the laws.

There are still concerns about the potential health impacts of e-cigarettes. ( Reuters: Regis Duvignau, file photo )

But Professor Simon Chapman from the University of Sydney warned potential dangers of the devices had not been fully investigated.

He said the product should be fully regulated before it is made available here.

"If someone was coming along with a cancer cure or an asthma cure and saying we need to get it out of the regulatory quagmire, people would say, that's not how we do things in Australia," he said.

"And that's why we need good quality evidence to inform us as to whether or not the net benefit to the community is as those who've succeeded with it, claim it is."

Professor Chapman questioned why manufacturers of the nicotine products had not submitted them for testing by the TGA.

"The question has to be asked, what are the manufacturers afraid of?" he said.

"Manufacturers of other nicotine replacement products have had to submit all the evidence that they were effective and safe."

But users like Alison Paul said delaying laws allowing the products could be costing lives.

"There's many people, particularly older people, who aren't willing to break the law to be vaping nicotine," she said.

"I'm firmly of the belief that the Government has got people's lives in their hands right now."

The parliamentary inquiry is expected to report back later this year.