The Chemistry of Secondhand Smoke

This article was written by Michael J. McFadden in his book "Dissecting Antismokers' Brains". His website is

The Chemistry of Secondary Smoke

As noted earlier in the chapter on Language, about 90% of secondary smoke is composed of water and ordinary air with a slight excess of carbon dioxide. Another 4% is carbon monoxide, a gas that can act as a poison when in sufficient quantity by reducing the amount of oxygen your red blood cells can carry. The last 6% contains the rest of the 4,000 or so chemicals supposedly to be found in smoke… but found, obviously, in very small quantities (1989 Report of the Surgeon General p. 80).

Most of these chemicals can only be found in quantities measured in nanograms, picograms and femtograms. Many cannot even be detected in these amounts: their presence is simply theorized rather than measured. To bring those quantities into a real world perspective, take a saltshaker and shake out a few grains of salt. A single grain of that salt will weigh in the ballpark of 100 million picograms! (Allen Blackman. Chemistry Magazine 10/08/01).

To refer back to our earlier example of arsenic, a nonsmoker would have to work with a smoker 8 hours a day, 5 days a week, 50 weeks a year, for well over a hundred years to be exposed to a quantity of arsenic equal to one grain of salt. While a lot of waitresses and bartenders may feel as if they’ve worked a hundred years at their jobs, there really aren’t too many who actually have.

And, again as noted earlier, far from all 4,000 of those chemicals are normally labeled as toxic in the first place, with the 1989 Surgeon Generals’ Report only noting that “some” are… without reference to how many or to what amounts would be considered toxic. One of the most basic principles of scientific toxicology is that “The Dose Makes The Poison.”… a fact always ignored by Crusaders.

When speaking of secondary smoke many Antismokers will also refer to the “40 carcinogenic compounds” it supposedly contains. In reality only six of those have in fact been classified as “known human carcinogens” (1989 Report of the Surgeon General. pgs. 86-87). Most of the rest of the 40 compounds have shown insufficient evidence of being human carcinogens and many are commonly found in foods, coffee, and the general environment (Science, 258: 261-265 (1992). The exposure of nonsmokers to the six actual human carcinogens is usually so minuscule as to be almost imaginary in nature and is sometimes far less than other everyday environmental exposures.

Secondary smoke is the mix of all of the smoke that enters the air in a room where someone is smoking, both the smoke exhaled by the smoker and the smoke coming off the tip of the cigarette. You’ve heard the claim that secondary smoke is twice as bad as what the smoker gets? In a way this is true: if you held your nose a quarter inch above the burning end of a cigarette and inhaled a slow deep breath through your nostrils you’d be getting a concentration of smoke and its chemicals twice as great as what the smoker is pulling into his or her mouth.

In the real world no one does that. Even the most hardened of smokers would generally be reduced to paroxysms of coughing from such concentrated inhalation. The secondary smoke that a nonsmoker comes in contact with is usually an extremely diluted mixture of exhaled smoke and the smoke produced directly from the cigarette’s tip.

Something that’s usually forgotten in the rush of concern about the nonsmoker is that the smoker is also breathing all the secondary smoke produced, and, given the closer proximity to the source, the smoker is inhaling it in far greater quantities and concentrations than most nonsmokers ever would! If the concerns about the dangers of secondary smoke were really true it would make perfect sense for a smoker with a smoking guest to insist that the guest go outside to smoke even if they were both smoking at the same time. Indeed, smokers would want to rush outside themselves out of fear of their own secondary smoke!

The exact chemical composition of secondary smoke depends largely upon how many seconds it’s been in the air. Just as happens in the case of most combustion products, the chemicals change and break down very quickly, and some elements will tend to settle toward the floor or deposit themselves on walls or curtains. In pursuit of some arguments Antismokers want to assume from the start that secondary smoke is carcinogenic: this is when they will claim that it’s chemically very similar to mainstream smoke. However, when they want to argue that comparing secondary smoke exposure to “cigarette equivalents” is unfair (This method generally produces very low measures of exposure… sometimes as low as six cigarettes per year even for bartenders), they will claim that it’s chemically very different than mainstream smoke and can’t be compared in that way!

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