I was thinking about an experiment with tobacco smoke, to be simple and visual for a class of sudents or pupils. I think the best is to light a cigarette and puss the smoke through a strong light source so that everybody can see the tiny smoke particles, filling the air of the room, which when breathed go into the lungs and  because  they are of the PM2.5 size are trapped in the pulmonary alveoli. Also,  hold a paper filter  (white , coffe filter or chemistry filters) in front of smoke , 6-7 smoke phases are trapped on the paper and give it a black colouration from tar. Collect tar in a vial to show it how black it is, . Then you can say that this smoke particles contain PAH, carcinogenic chemicals, nitro-PAH,  VOCs, benzene, CO, etc. Also, they have polymeric black colour carbonated particulates that trap stable free radicals producing continuously hydroxyl radical which can penetrate into cells and can cause DNA damage. or oxidize lipids in cell membranes. These pictures can be found in books, and projectd on backboard. See my papers on tobacco smoke. in Researchgate. Also, passive smoking can be explained with a smoking a cigarette and allowing to produce secondary smoke which is more dangerous because of lower temperature and pyrolytic burning  in the tip (the smoke covers the cigarette tip prohibiting oxygen to do the oxidizing burning, and in this way is producing more carcinogens. 

Valavanidis A, Professor

Thanks, this was very helpful. I think I have what I need :)

Dear Chr Rothlein,

An addition to the first suggestion. You can collect the filters from the cigarette (5-10) before smoking and after smoking. Open them and break it into small parts to see the interior and put them into two separate bottles. The original are white or clear, while the ones after smoking are black-brownish. The filters have special features (microfilters) for absorbing tar and particles. You take the black filters and put them  into water (or alcohol, or acetone for better extraction),  shake well  the bottle, to extract the carbonaceous tar, the liquid turns blackish-brown. This is what happens in the lungs and deposit in  the alveoli carcinogenic and mutagenic compounds (polycyclic aromatic hydrocarbons,(PAH), nitro-PAH, organic and inorganic substances with toxic  properties). You can do the experiment before or during a demonstration in front of students for experimental reality purposes. Do not use the word toxins, but toxic (oxidants, carcinogens, alkylating, toxic to liver, inhibitors to enzymes, etc) chemical substances or compounds for the chemical substances of tobacco smoke, is not correct.

A, Valavanidis

You can find different experiences at Youtube like this:https://www.youtube.com/watch?v=6r2vgxnC3D4 You can also measure the CO and compare between an smoker and a not smoker results or using a cigarette directly in the filter. It's quite spectacular how the level is increasing. Nicotine is not possible to obtain in a simple experiment.

Antoni Baena