The main thing that smokers are addicted to is nicotine, which is a drug that your brain starts to crave after you’ve been exposed to it.  There’s more than 4000 chemicals in cigarettes, and they come from a variety of sources.  Some of them are in the tobacco plant itself, absorbed from the air by the plants including chemicals such as polonium.  Some chemicals are produced when the tobacco is processed, some are added in when cigarettes are made.  The most dangerous chemicals in tobacco are actually created when you burn a cigarette; the chemicals of burning are produced by the act of lighting a cigarette and inhaling something that is burning.

There are a few extra chemicals added during the process of making a cigarette, and so smoking straight tobacco would lack these, but the important chemicals are created by the simple act of burning the tobacco.

A lot more information is available from Cancer Research UK’s smoke is poison campaign, www.smokeispoison.com.

Dust is mainly human skin cells.  The average person loses between 50-100 thousand skin cells every minute.  Those flakes of skin accumulate in carpets and furnishings, dry out and then are lifted into the air by drafts or air currents.

Because dust mainly consists of skin cells, it’s nutritious and there are some things that will eat it.  House dust mites are a microscopic organism which eat these skin cells –asthma sufferers are often allergic to their poo, which is carried into the air, and can irritate the lungs.

We put this question to Gavin Laing, of the Liverpool School of Tropical Medicine:

Okay, antivenom has been around for at least 100 years, but the techniques of producing antivenom have not really altered a lot in that time.  What normally happens is a very large animal is immunised over a long time with very small amounts of snake venom, so it won’t harm the animal; traditionally they have used horses.

Chris:  So what you would do is milk the snake, get some of its venom and then inject that into the horse.

Gavin:  Yes, in very small quantities, so the horse will not be affected at all, it’s only a tiny amount.  The horse will then raise antibodies against this antigen that’s been injected in the same way that humans immunised with smallpox would be raising antibodies against that.

Chris:  So the horse gets antibodies in the bloodstream.

Gavin:  That’s correct, and over a long period of time, say eight months or so, the horse will then become hyper-immune.  Every so often, some serum is then drawn from the horse and immunoglobulins are purified from that, and from that you can split the immunoglobulins into smaller components such as the FAB or the FAB prime-2.  And these would then be infused intravenously to a person who presents themselves in hospital who has been envenomed.

Chris:  And so the antibodies would, in that victim, lock on to the venom and neutralise it?

Gavin:  They would.  They would seek out the circulating venom in the patient and immobilise it.  They would form an immune complex and would be completely harmless and would then be flushed away normally.

You can read the whole interview with Gavin here, or listen to it as part of the podcast.