The Labour-controlled Welsh Assembly in Cardiff Bay is hoping to pass its Public Health (Wales) Bill in the Senedd.
If passed, the Bill would become a UK first and would restrict the use of nicotine inhaling devices in certain public places - such as schools, places where food is served and on public transport.
The move has been criticised by opposition parties and even divided opinion among health charities.
However, Health Minister Mark Drakeford insists the legislation will protect people from harm - and the curbs on e-cigarettes would make smoking less appealing to youngsters.
He said: “The Bill will help us to respond to a range of public health threats in Wales, including the risk of re-normalising smoking for a generation of children and young people who have grown up in largely smoke-free environments.
“It is the government’s responsibility to create the conditions, which enable people to live healthy lives. This Bill strikes a balance between those actions which will make a big difference to people’s health without intruding unduly on the rights of individuals to run their own lives.”
If passed the bill could set a precedent which may see e-cigs banned in England.
It comes as new research shows vaping can “compromise” the function of the immune system in the airways more than tobacco and flavourings were the worse.
But, Cancer Research UK said there was not “enough evidence to justify an indoor ban on e-cigarettes”.
And in its evidence to an Assembly committee, The British Heart Foundation said: “It is heavy handed to regulate them as if they were cigarettes.”
However, the British Medical Association Wales said it was in favour - arguing it is better to be safe than to be sorry.
And health body Public Health Wales’ added: “We cannot sit around and wait a couple of decades to see whether or not the conclusive evidence that people might like to see is available before making a judgment.”
In America, the US Food and Drug Administration (FDA) classifies many liquid flavourings in e-cigarettes as “Generally Recognised as Safe.”
Researchers from the University of North Carolina School of Medicine point out this classification is designated for oral consumption.
Yet most flavourings have not been tested for their effects on the respiratory system.
Professor Ilona Jaspers said: “The digestive systems and respiratory systems are very different.
“Our stomachs are full of acids and enzymes that break down food and deal with chemicals; this environment is very different than our respiratory systems.
“We simply don’t know what effects, if any, e-cigarettes have on our lungs.”