Electronic cigarettes have come a long way from the original Ruyan design - and indeed from the 1963 smokeless cigarette patented by Herbert A. Gilbert in 1963.

However, the basic concept is still the same.

Nicotine is dissolved in a solution consisting of water and propylene glycol. Propylene glycol is a solution which is used in many other food stuffs and medicines and, according to Dr Murray Laugesen of Health New Zealand, consists of two extremely safe molecules.

Critics of the electronic cigarette claim that this propylene glycol is also present in anti-freeze. That's pretty meaningless. Flour can be used to make bombs, which doesn't mean that flour is dangerous in and of itself. We also like to point out the other ingredient found in both electronic cigarettes and anti-freeze - water!

When a user wants his intake of nicotine, he drags upon the e-cigarette. The inflow of air activates a microprocessor which prompts an internal atomizer to push tiny droplets of the nicotine/proylene glycol solution into the airstream.

The propylene glycol combines with the air to produce both the satisfaction, feeling and appearance of tobacco smoke. However, there is no tobacco involved in the process.

Within a few seconds of the solution being blown out, it disappears completely.

Experts believe that because there are very few carcinogens in those electronic cigarettes tested by the FDA (concentrations of those nitrogen specific carcinogens that were found were thousands of times lower than those in regular cigarettes, and similar in concentration to those found in many food stuffs), and because no combustion takes places, electronic cigarettes are safer than regular cigarettes. However, long term studies that confirm those theories have not yet been carried out.

Some companies have also suggested that the electronic cigarette could help nicotine cessation.

New Zealand research shows that the electronic cigarette can help relieve nicotine cravings and increase the level of nicotine in the blood, while surveys suggest that electronic cigarettes can at least replace cigarettes.

However, until long term studies prove that nicotine cessation can be used with electronic cigarettes companies in the UK and the US may not legally market them as cessation devices.