Lead author Professor David Thickett said that while e-cigarettes are safer than traditional cigarettes, they may still be harmful in the long term. "But if you vape for 20 or 30 years and this can cause COPD, then that's something we need to know about".
Research on e-cigarettes has been a bit of a moving target, said Dr. Michael Blaha, a professor of medicine and director of clinical research at the Ciccarone Center for the Prevention of Heart Disease at Johns Hopkins Medicine in Lutherville, Maryland.
In order to arrive at the conclusion, researchers devised a mechanical device that mimicked vaping at the laboratory. A large number of e-cigarette companies are being bought up by tobacco companies and there's certainly an agenda to portray e-cigarettes as safe. The US Surgeon General has however issued warnings that use of e-cigarettes among the young can lead to several problems such as nicotine addiction, mood swings and impairment of brain development.
Previous studies have focused on the chemical composition of e-cigarette liquid before it is vaped.
They extracted immune cells from lung tissue samples provided by eight non-smokers who had never suffered from asthma or COPD and exposed them to varying levels of e-cigarette fluid and condensed vapour.
The vaping process damaged the vital immune system cells, they concluded.
According to Thickett, the vapour produced by an e-cigarette boosts the production of inflammatory chemicals and disables key protective cells in the lung that keep the air spaces clear of potentially harmful particles.
"However, since electronic cigarettes are used nearly exclusively in the United Kingdom by current or former smokers, the key question is how this adverse effect compares with that of exposure to cigarette smoke".
What is more, the ability of cells exposed to vaped condensate to engulf bacteria was significantly impaired, although treatment with an antioxidant restored this function and helped lessen some of the other harmful effects.
Prof Thickett then shared that he believes e-cigarettes are less harmful than ordinary cigarettes but he warned people to be wary about its safety.
E-cigarettes don't proceed tar or carbon monoxide; two of the main toxins in cigarette smoke, said the NHS.
Public Health England (PHE) has told smokers that vaping is a preferable habit because it "poses only a small fraction of the risks" and switching completely from smoking to vaping conveys "substantial health benefits".