Tobacco control campaigns frequently make use of statistical and scientific information to inform the public and policy makers about the dangers of tobacco smoke. It is clearly crucial for the credibility of tobacco control programmes that accurate scientifically valid information is used in these campaign materials, and Siegel1 highlights the importance of ensuring that the evidence base of these materials is scientifically sound.
In 2002, the British Medical Association produced a report on passive smoking that indicated:
“Almost 85 per cent of secondhand smoke is in the form of invisible, odourless gases.”2
This referenced a US National Research Council report3 as the source of this information, but this report does not directly explain the 85% figure. At no point does the US report suggest that 85% of secondhand smoke or environmental tobacco smoke (ETS) is invisible.
However, despite the lack of unambiguous scientific evidence, the suggestion that 85%…