Hi again Laura,
That’s an important question and thankfully with the laws against smoking in public something is being done about it. Smoking is harmful in the short term because of the many strange products they put in cigarettes like Tar, Arsenic, Carbon Monoxide… and the list of cancer-causing agents goes on, some of which haven’t even been indentified yet! Small amounts of these get in the body once the cigarette is burned and inhaled, but they build up over time. Non-smokers who are unfortunate to breath in the exhaled smoke from a cigarette are less at danger because the smoker himself/herself has “filtered” out some of the bad ingredients, but there are so many some are still released and will get into a non-smokers lung.
So why do people smoke if it’s so bad for them? Cigarettes contain Nicotine. Nicotine is a highly addictive drug, ranking up there with Heroine (a lot less socially acceptable). Nicotine is a chemical that acts like the brains own chemicals called neurotransmitters. Nicotine stimulates the body to produce Adrenaline (another neurotransmitter) which gives the sense of being alert or focused. Nicotine gets into the brain and binds onto the receptors for these signals (called Nicotinic Acetylcholine Receptors). These receptors usually bind onto a neurotransmitter called Acetylcholine, and they tone down the release of the neurotransmitter Dopamine (I mentioned in the previous post). Nicotine increases Dopamine release when it binds to these receptors. A study in 2011 scaned the brains of smokers and non-smokers who shared a car ride (when the smokers smoked) after they were given a reagent that labels the Nicotinic Acetylcholine Receptors in their brains. The scientists were able to see that the receptors in non-smokers brains had become highly bound by Nicotine after just 1 hour of exposure to second hand smoke in the car. This was direct evidence that enough Nicotine is released by passive smoking to effect other people around them.
An interesting question now is will smokeless cigarettes, electronic cigarettes, help to reduce this? However, those e-cigarettes still contain addictive nicotine and release certain chemicals too (albeit from just one end of the cigarette), while they may seem like an improvement European Agencies say that it is too soon to know how they affect non-smokers standing by. So we should be careful and more research needs to be done.