Customers who purchase e-cigarettes could be putting their health at risk, a study has warned.

Researchers from the University of Athens said e-cigarettes could be harmful to the lungs after looking at their short-term effects on 32 people, including eight who had never smoked and 24 smokers, some with and some without existing lung conditions.

Researchers said e-cigarettes could be harmful to the lungs after looking at their short-term effects on 32 people

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After smoking an e-cigarette for 10 minutes, the researchers found there was an immediate rise in airway resistance among non-smokers and smokers with normal spirometry. In COPD and asthma patients, however, there was no recorded effect on airway resistance. Professor Christina Gratziou, one of the study's authors and chair of the European Respiratory Society Tobacco Control Committee, said the research suggested e-cigarettes caused "immediate harm".

"We do not yet know whether unapproved nicotine delivery products, such as e-cigarettes, are safer than normal cigarettes, despite marketing claims that they are less harmful," Ms Gratziou highlighted.

Responding to the findings, pharmacy technician Leanne Beverley of Monarch Pharmacy, Coventry, called for more research on whether e-cigarettes were a safe and effective smoking cessation aid. And she argued for tighter regulation of the e-cigarette market. "I've heard e-cigarettes are being sold on market stalls," she told C+D.

Mohammed Patel, who works for Coventry Healthy Lifestyle Services and oversees the local pharmacy smoking cessation programme, said the research was further evidence of why pharmacies should advocate their in-house stop smoking services, which offered "behavioural support and evidence-based stop smoking aids".

But Nader Siabi, owner of the Trio Pharmacy, Shepperton, said the study "was not big enough to draw any conclusions" and that patients should be given information about all smoking cessation products to enable them to make informed choices.