electronic cigarettes and air pollutionElectronic cigarettes and air pollution are two widely mentioned topics in the world and many question if the two interact with each other – in other words, do electronic cigarettes contribute to air pollution with their "cigarette smoke"?

An electronic cigarette is a type of device called an electronic nicotine delivery system.  Shops selling electronic cigarettes have become an increasingly common sight all over the UK, and there are already around 2 million users of the devices. They are marketed as being “healthier” for those who have found it hard to give up nicotine in tobacco, because it does not involve any exposure to tobacco smoke and its known health hazards.

What does an e-cigarette actually contain?

An e-cigarette consists of a battery, a heating element and a solution-filled cartridge. The solution itself contains nicotine, a chemical called polypropylene glycol (which keeps the mixture liquid) and various flavouring agents.

How does an e-cigarette work?

The heating element inside the device heats up the solution, this creates a nicotine-containing aerosol which the user then inhales. The 'smoking' of an e-cigarette is called 'vaping'.

So, what is the actual difference between an e-cigarette and a conventional cigarette?

There is no burning of tobacco in an e-cigarette, so no cigarette smoke is created.

What is in the vapour emitted by an e-cigarette?

Many users will tell you that the emissions from electronic cigarettes are harmless water vapour and there is, therefore, no need to ban the use of these devices indoors; as has occurred in many places.  This is not true. Studies have shown significant levels of: nanoparticles, formaldehyde, benzene and nitrosamine in electronic cigarette emissions. For instance, a recent report from the Centre for Environmental Health reviewed around 100 different e-cigarettes, they found that 90 per cent of them emitted significant amounts of formaldehyde and/or acetaldehyde. This would give credence to the idea that electronic cigarettes and air pollution do relate with each other.

Are e-cigarettes likely to have any long-term health impacts on either the user or those around them?

The dangers of nanoparticles are well known as they can be inhaled deep into the lungs causing inflammation and exacerbating heart and lung disease. Formaldehyde, acetaldehyde, nitrosamines and benzene are all known carcinogens. Studies on mice and cell cultures suggest that the vapour from electronic cigarettes can damage the cells that line the bronchi of the lungs, this makes it harder to resist bacteria and viruses. This suggests that exposure to electronic cigarette emissions could be particularly harmful to those who already suffer from a lung condition like chronic, obstructive pulmonary disease. Long-term exposure to nicotine itself is also a concern.

What we don't have at the moment is evidence from long-term human studies on whether there are significant health risks from either using electronic cigarettes, or being exposed to the vapours in the same way as non-smokers are exposed to environmental tobacco smoke. Despite there being no concrete proof that electronic cigarettes and air pollution do interact with each other, it seems wise to apply the precautionary principles and assume that these devices (like diesel exhausts) are maybe one more source of air pollution. Until we know more about the health effects, the control of where they can be used (public spaces) may need to be applied.