The Electronic-Cigarette Association of SA, which represents importers and manufacturers of e-cigarettes, is urging smokers to switch from lighting-up to "vaping".
E-cigarettes are battery-operated inhalers that deliver a hit of vaporised nicotine without burning tobacco - the cause of most lung cancers.
On Saturday, the association erected a billboard overlooking the N1 highway in Johannesburg with the phrase: "E-Cigarettes Save Lives."
The line is from an article in the UK's Spectator magazine by Dr Derek Yach, a former head of tobacco control at the World Health Organisation.
Yach, now the South African head of the Vitality Institute, contends that e-cigarettes are "harm-reducing". He states that evidence shows that people smoke for the calming effects of nicotine but die from the tar in cigarettes.
He proposes that switching to e-cigarettes be encouraged because they give both a nicotine hit and the health benefits gained from quitting smoking. His view has been endorsed by the British Royal College of Physicians.
A recently released Global Burden of Disease study shows that last year lung cancer was the leading killer among all cancers.
To change this, Yach told The Times, "we need a serious focus on quitting smoking, and using reduced-risk products such as e-cigarettes and pharmaceutical nicotine replacement".
"Nicotine use does not cause lung cancer but public and doctor perceptions suggest that it does," he said
The WHO is being lobbied by health experts to regulate e-cigarettes, with South African Health Minister Aaron Motsoaledi saying he wants stricter regulation of their sale and use.
In response, Yach told The Times that if the campaign against e-cigarettes succeeded smokers would be left with a "50% probability that they would die from smoking".
E-cigarette critics say that "vaping" will "renormalise smoking" after years of high taxes, and bans on indoor smoking and on advertising, had denigrated the practice.
The SA National Council Against Smoking worries that the "fun flavours" of e-cigarettes will encourage teenagers to start vaping and become addicted to nicotine. But, counters Yach, this is no more likely than it would be for non-smokers using a nicotine replacement gum.