E-cigarettes: 'Vapers have to stand in the smoking shed'
People will be banned from using e-cigarettes in enclosed places like restaurants, pubs and at work in Wales, under a new public health law.
It has already divided health and medical groups, including some anti-smoking campaigners.
But ministers believe the controversial move - a UK first - is a "balance of risk" and will stop children smoking.
Health Minister Mark Drakeford said he was convinced he had got the balance right.
But others are worried the evidence of e-cigarettes being a "gateway" to children becoming smokers is not there.
Dr Graham Moore is a research fellow at Cardiff University's Centre for the Development and Evaluation of Complex Interventions for Public Health Improvement (DECIPHer) and Jim Salter, from Celtic Vapours, which makes liquid for e-cigarettes in Swansea.