Businesses should create indoor ‘vaping’ rooms so that staff can indulge in e-cigarettes without going outside, according to Public Health England (PHE).
The guidance also advises that employees are given extra break-times for their habit and urges employers to make the vaping devices a "more convenient option" - to encourage workers to give up traditional cigarettes.
Workers should not be forced to vape outdoors - in places set aside for regular smokers - because this will "undermine their ability to quit smoking", the advice says.
The guidance advises businesses: "Vapers should not be required to use the same space as smokers, as this could undermine their ability to quit smoking and stay smokefree, particularly among those most heavily addicted.
"To maximise the number of smokers switching to e-cigarettes, vaping should be made a more convenient, as well as safer, option."
An indoor space is suggested, because "forcing smokers outdoors has increased public visibility of smoking, including to children and young people".
E-cigarette vapour can be irritating to people with asthma and other respiratory conditions, it admits and their needs "should be taken into account".
But vaping should be only be banned outright in schools or other workplaces where children are present, the guidance states.
Extra break times for e-cigarette users
E-cigarettes deliver a smaller nicotine hit than traditional cigarettes, so users should be allowed extra breaks for the "frequent interim top-ups" they need, the advice says.
Public Health England estimate smokers require only "one cigarette every hour or so, and in a short space of time" to achieve the blood nicotine level they crave.
In contrast, the advice states: "Vaping provides a generally lower blood nicotine level and takes longer to reach a desired level, requiring frequent interim top-ups.
"This difference should be taken into account, particularly when developing policies for workplaces."
Industry welcome and disputed evidence
The Electronic Cigarette Industry Trade Association (ECITA) has welcomed the news.
Chief Scientific Officer Tom Pruen said: "The guidance from Public Health England is pragmatic and sensible, and if adopted by employers will help them to better provide for the health and well-being of their staff.
"Allowing the use of e-cigs will benefit not just the physical health of their employees, but also boost morale and job satisfaction as well as encouraging more existing smokers to switch to the safer alternative of vaping.
"The guidance from PHE is another recognition of the potential for e-cigs to offer huge improvements to public health."
Professor Kevin Fenton, National Director of health and wellbeing at PHE, said: "The evidence is clear that vaping is much less harmful than smoking and that e-cigarettes are helping many smokers to quit.
"This new framework will encourage organisations to consider both the benefits and the risks when developing their own policies on e-cigarettes.
"Different approaches will be appropriate in different places, but policies should take account of the evidence and clearly distinguish vaping from smoking."
PHE has abandoned the "precautionary principle" towards e-cigarettes after concluding that they are around 95 per cent safer than smoking.
However, PHE has been criticised previously for their stance on e-cigarettes by peer-reviewed medical journal The Lancet.
In a 2015 editorial entitled ‘E-Cigarettes: Public Health England’s evidence-based confusion’, The Lancet called the evidence which formed the basis of PHE’s ‘95 per cent safer’ claim “methodologically weak” and highlighted declared conflicts of interest surrounding the funding of the study.
The criticism centred around a paper published in European Addiction Research, by Professor David Nutt, which The Lancet says was based on the opinions of a ‘small group of individuals with no prespecified expertise’.
The Lancet also raised questions over the impartiality of the paper, with co-authors of the study reporting having worked in advisory capacity with e-cigarette distributors and ‘manufacturers of smoking cessation products’.
The Authors of the PHE report later published a response defending their conclusions and citing other evidence to back up their claim.