In the case of the smoker, it could (wrongly, as we have seen) be argued that the risks were somehow voluntarily incurred. In the case of the passive smoker, that argument would be far harder to sustain. Passive smokers do not themselves light up. They merely breathe. You can voluntarily choose to do something only if you can, realistically, choose not to do it; and no one can choose not to breathe. Since passive smoking—or, more technically, "exposure to environmental tobacco smoke"—"generally occurs as an unavoidable consequence of being in proximity to smokers, particularly in enclosed indoor environments," the surgeon general prefers simply to define passive smoking as "involuntary smoking."
Smokers might sometimes have sought and been granted the permission of all nonsmokers in the vicinity for them to light up. Assuming that that consent was given freely (i.e., that it was not a tyrannical boss 'asking' permission of a secretary) and that it was based on full information about the hazards of passive smoking, nonsmokers' exposure to environmental tobacco smoke would indeed then be voluntary. Given the dangers of duress and of fraudulent claims that rights have been waived, we may prefer to treat the right to clean air as if it were as inalienable as the right to life itself. But in any case, this whole voluntary waiver scenario is plausible only among moderately small groups of people.
Among larger and more anonymous groups, the only sense in which passive smoking might be thought to be voluntary would be insofar as people voluntarily enter environments they knew were or would become smoky. Thus, it might be argued that if people do not want to breathe other people's smoke, they should not go into notoriously smoky places like English pubs.
There is, of course, the question of why nonsmokers should banish themselves rather than smokers controlling themselves. In any case, there is a range of places it is unreasonable to expect people to avoid going. One is to work. Another is onto public transportation. Another is into public buildings. Another, perhaps, is to public entertainments (restaurants, theaters, and such like). If people cannot reasonably be expected to avoid going to work, and getting there by public transportation, then the Humean doctrine ("no consent without the possibility of withholding consent") would imply that they have not voluntarily consented to the risks of passive smoking in those places, either.
(Robert E. Goodin, "The Ethics of Smoking," Ethics 99 [April 1989]: 574-624, at 601 [footnote and parenthetical references omitted])