# How long burned tobacco smoke remain toxic?

It's hard to evaluate Environmental Tobacco Smoke lifecycle, it can certainly react, be absorbed by organisms, or be diluted in rain, and be emitted again from the ground.
But in the end, I'm interested to understand (as a non expert) if the toxicity (cytotoxicity, genetoxicity) of the compounds decrease over time (especially how are they eliminated) in a global outdoor environment where we suppose emissions would stop

Several resources list the components Chemistry and Toxicology of Cigarette Smoke, Comparison between Marijuana and Cigarette Smoke, CAEPA (page6):

Gas and particle phase contain roughly the same constituents as explained in the first paper, some compounds are 1,3-butadiene, acrolein, ammonia, aromatic amines, benzene, CO, isoprene, nicotine, nitrosamines, PAHs (polycyclic aromatic hydrocarbons), pyridine, toluene, hydrogen cyanide...

What could be their half-life in outdoor environment?

• Tobacco smoke is never toxic the chemicals are too low concentrations- only irritative. Otherwise it would be kill too many smokers immediately. – user2617804 Jun 9 '14 at 8:52
• long-term toxicity? without much medical/biologic knowledge, when I see the differene between the skin, the voice of a smoker and a non-smoker, I imagine there are consequences on any other cells, neurons, and biological processes – caub Jun 9 '14 at 12:43

# Toxicity of tobacco combustion products in different phases

For answering your question I think is better split it in two. First thing you need to understand that toxicity depends on the method of administation of the toxic agent. Tobacco smoke is a physical state of the tobacco combustion products. It is an aerosol originating from combustion where its particles are liquid, gas and solid (tar). Quoting Chemistry Central Journal 2012, 6:98

Cigarette smoke is a complex and dynamic aerosol consisting of at least 5,600 chemicals and toxicants found across two phases, the particulate (tar) and vapour phase.

(I would like to add the gas phase...) so when the product of the combustion of the tobacco are in this physical state you have to look at a different method of administration in this case vapour inhalation, Dust and Mist Inhalation and gas inhalation these are the most potentially dangerous method of administration. It seems that after about 40 minutes the liquid and solid part of the aerosol deposit (of course this depends on the condition, T, wind etc. etc.) so is probable that after this period of time the toxicity of tobacco combustion products decrease considerably. However this is not true for all the combustion products. For example: carbon monoxide is recognize tobacco combustion product and it is a gas so it wont deposit after this time and it will be "removed by reactions with OH radicals (85%), by soils (10%), and by diffusion into the stratosphere" very slowly. Benzene is a good example of how the toxicity depends on the method of administration. LC50 inhalation value of benzene is 10000 ppm TFLo Dermal is 0.92 mL/kg so it is a big difference if you wait that the areosol deposit or if you inhale it.

If you are interested in rate of decomposition of benzene it seems that biodegradation of benzene can reach 0.95% at day according to Chiang.

Regarding 1-3 butadiene according to William A. McClenny and Donald Whitaker:

i.e., a 10-6 lifetime risk level for cancer due to inhalation exposure of 0.03 $g/m^{3}$ (12.4 pptv at 20 °C and 1 atm pressure).1 This compound is very reactive in the ambient atmosphere with a short atmosphericlifetime, estimated to be 2–3 hr.

The half-life of acrolein is 14.4 hr.

You can also find a very complete EPA report EPA/600/P-98/001F October 2002.

However determine the half-life of all the compounds is a very complex task because is related to how the ecosystem respond to these compounds so to the actual capability to decompose them through different mechanism is strictly related with thousands of factors.

• Thanks, a good answer in my opinion, so this is more a matter of time than distance, (even if distance in general help with dispersion). I'm pretty worried by smokers, and feel the harm is proportionnal to the quantity inhaled and have no lower limit (where our body would handle this extra-toxicity), so in my opinion we are all in danger. I wonder how the combustion of simple natural tobacco/marijuana is so concerning (additives in industrial cigarettes don't show a significant difference) – caub Jun 13 '14 at 12:36
• @dvok you are welcome. I agree with you, probably compered with other major dangerous behavior a passive smoker doesn't have to worry much but I think that indeed smoke can cause damage not only to the smoker... – G M Jun 13 '14 at 13:05
• @dvok P.S. however distance is very important because the smoke diffuses so I would say that is a matter of both. – G M Jun 14 '14 at 9:46