Anti-smoking activists have made some ridiculous claims about smoking and the associated health risks. In recent years, studies have suggested that movies encourage teenagers to pick up the habit, any exposure to secondhand smoke is dangerous, and that such a thing as ‘third hand smoke’ exists. But a new study in Environmental Health may be the greatest example of exaggeration on the issue ever. The study argues that smokers may be doing additional harm to themselves with their own secondhand smoke.

The prevailing assumption is that the risks secondhand smoke poses to smokers would be negligible in comparison to those posed by actually smoking. But the authors of the current study say there is little evidence to substantiate that assumption and instead suggest that for someone who smokes 14 cigarettes a day, their own secondhand smoke may result in exposure the equivalent of smoking an extra 2.6 cigarettes.

So how did they end up with that very specific number? They studied the exposure of newsagents in Genoa, Italy to their own cigarette smoke. Lead author Maria Teresa Piccardo explains that, "Newsagents were chosen because they work alone in small newsstands, meaning that any tobacco smoke in the air they breathe is strictly correlated to the number of cigarettes smoked by that newsagent. We studied the contribution environmental tobacco smoke made to carcinogen exposure in 15 active smokers."

Most of the news reports on the study simply left it at that, and chances are that most readers will get the impression that smokers are being harmed by their own secondhand smoke. But the study itself contains a very obvious error that was glossed over in the news reports. Newsagents who participated in the research “spend 12 hours a day in small (about 4 m2) naturally ventilated newsstands;  b) newsstands are completely closed and only with a window to serve clients…”

Now if somebody plans to spend most of their day in a confined space filled with tobacco smoke, there’s probably elevated risk associated with that environment. But how common  is it for the average smoker to spend 12 hours in a space equivalent to a newsstand? Yes, people smoke in their cars, homes, and in bars (if allowed to), but none of those seem even remotely similar to a box designed to fit one person.

the authors concluded that active and passive smoking need to be considered in research about the health of regular smokers, which is a reasonable suggestion. But the next time similar research is done, it may be a good idea to study conditions that actually apply to most smokers.

Citation:  Maria Teresa Piccardo, Anna Stella, Federico Valerio, 'Is the smokers exposure to environmental tobacco smoke negligible?', Environmental Health, January 2010, 9(5); doi:10.1186/1476-069X-9-5