Vaping shops are opening at a rate of more than two a day despite major concerns about the effects of e-cigarettes on health.

There are now more than 1,700 shops across the country, half of them opening in the last year alone, figures show.

The highest concentration of the shops, which sell only electronic cigarettes, liquid nicotine for use with them and accessories, are in the North of England, Scotland and London, industry body ECigIntelligence found.

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Vaping shops are opening at a rate of more than two a day despite major concerns about the effects of e-cigarettes on health. Pictured is a vaping shop in Covent Garden, London

The battery-powered devices heat up the liquid so it can be inhaled as a vapour.

Their popularity has soared over the last ten years and there are now more than three million ‘vapers’ in Britain after e-cigarettes were billed as a healthier alternative to smoking.

The Royal College of GPs has told its 52,000 members to advise patients who are trying to give up smoking to switch to e-cigarettes, as they give a nicotine hit without many noxious chemicals found in cigarettes.

Public Health England has said e-cigarette use carries ‘a fraction of the risk of smoking’.

But the British Medical Association called earlier this year for a ban on vaping in public places and critics argue the effect on health over the long term is not yet known as they have not been around long enough.

And earlier this month, the US government issued a stark warning that electronic cigarettes could leave children hooked on nicotine for life.

America’s top doctor, Surgeon General Dr Vivek Murthy, said the devices were a ‘major public health concern’ and said vaping was a ‘gateway’ to smoking for teenagers, who can become hooked on nicotine after as little as one to three days of it a month.

Scientists at the world-renowned Karolinska Institute in Stockholm have also raised concerns, claiming just ten puffs on an e-cigarette are enough to trigger physiological changes which could lead to heart disease.

Nearly three million people in Britain use e-cigarettes after they were billed as a healthier alternative to smoking

And the EU banned TV advertising of e-cigarettes earlier this year because of concerns about the risk to children.

It said: ‘Electronic cigarettes can develop into a gateway to nicotine addiction and ultimately traditional tobacco consumption, as they mimic and normalise the action of smoking.’

Other studies have found e-cigarettes raise blood pressure and promote a hardening of the arteries just like normal cigarettes.

But traders are cashing in on the trend.

More than 800 new shops stocking the devices opened in the last 12 months, according to the latest research.

Barnaby Page from ECigIntelligence said this was because vape stores offer customers more detailed knowledge than they could get from other retailers, and a wider selection of stock.

The stores are opening in central locations, though often not on prime High Street sites.