5 things you need to know about e-cigarettes
- Vaping had been seen as a healthier alternative to traditional cigarettes, but a rash of illnesses and deaths suggests that might not be true

E-cigarettes have become hugely popular in the past decade but a rash of vaping-linked deaths and illnesses in the United States is feeding caution about a product, already banned in some places.
Here are five things to know about electronic cigarettes.
Around for two decades
Early designs for an electronic cigarette were drawn up in the United States in the 1960s, but Chinese pharmacist Hon Lik is acknowledged as the inventor of a viable commercial version in the early 2000s.
Hon, who was trying to quit his own pack-a-day habit, took out patents between 2003 and 2005. But his devices would soon be overtaken as the international market exploded.
How do they work?
A battery powers a coil that heats a liquid containing various amounts of nicotine as well as propylene glycol and vegetable glycerin, which mimic tobacco smoke when heated.