New York

Long-term e-cigarette use could lead to chronic lung conditions, scientists have warned. US researchers found e-cigarette vapour affects cells in the lungs in the same way as cigarettes smoke, even after just one hour. Long-term exposure could lead to emphysema, which is also known as chronic obstructive pulmonary disease, or COPD.

Although these were preliminary results, experts have hailed the results as significant. Dr Nicholas Hopkinson, medical adviser to the British Lung Foundation, told MailOnline: 'Most people are fairly confident that e-cigarettes are less harmful than cigarettes. 'The question now is whether they are harmless, and there is now evidence which shows there is some harm.

'A particular concern is people with lung disease who are smoking.' COPD is an umbrella term used to describe chronic lung diseases that limit the air flow to the lungs and includes diseases like 'chronic bronchitis' and 'emphysema'.

The most common symptoms of COPD are breathlessness, or a 'need for air', and excessive production of mucus in the lower airways. It is not just simply a 'smoker's cough', but an under-diagnosed, life threatening lung disease that may progressively lead to death, the World Health Organisation warns.

According to its latest estimates, currently 64 million people have COPD and 3 million people have died of COPD. WHO predicts that COPD will become the third leading cause of death worldwide by 2030. As part of the study, US researchers examined how e-cigarette vapour compares to tobacco smoke by testing how it affects cells. They exposed human bronchial epithelial cells – cells from the lining of the bronchi, the network of tubes used to convey air to the lungs – and exposed them to e-cigarette vapour from one to six hours.

The team found even minimal exposure of e-cigarette vapor for one hour, disrupted the protein processes in cells 'significantly'. This is the same path cigarette smoke and second-hand smoke takes in our bodies, they said. Protein homeostasis or 'proteostasis' is the process that regulates proteins within cells in order to maintain the health of the cell and the organism itself.

In the lungs, the small air sacs, known as alveoli, have walls made of protein. So proteostatis is the normal process in which this protein is broken down and regenerated so they can function properly. If proteostasis is disrupted, if the alveoli become damaged, they do not regenerate, meaning the lungs cannot carry out its function of oxygenating blood as well.