What they are is *relatively* harmless compared to lit tobacco, which is not only a perfectly valid piece of objective assessment based on the evidence we have, and the materials science we know extremely well (although in a slightly backhanded way e-cigarette use long term might be like losing the tips of all your fingers, whereas smoking is like being run over a series of articulated lorries, that are on fire, such is the massive harm smoking does) but that relative harm *is* the actual important point
irregular heartbeat or palpitations occur
The tar and nicotine particles embed themselves into your cars fabric, carpet, headliner, air vents, and even the foam under your seats
While the benefits of quitting smoking are vast, long-term smoking (1020 years) can cause chronic obstructive pulmonary disease (COPD), which includes chronic bronchitis or emphysema, from which the lungs never fully recover or heal