Last year, my university debated the introduction of a ban on smoking on all areas of its campuses, after the senate alumni representative and Herald columnist Peter FitzSimons led the charge. To the surprise of some, I spoke against banning it entirely. I supported bans near buildings, because of significant smoke drift into offices, and in outdoor eating areas, because of the sardine-like proximities and the easy option for smokers to move away.

But I wanted nothing of banning it on the big campus boulevards or lawn areas. I know of no evidence that the fleeting encounters you can get from walking past a smoker in a wide-open space can cause any disease. The campus is now smoke-free, save for four outdoor smoking zones.

While it is true that there is "no safe level of exposure to tobacco smoke", it is also true that to set public policy aiming for zero risk would cause mayhem and a good bit of duplicity. Tobacco smoke contains many carcinogens and irritants, but so does smoke from any source. I didn't hear any calls around the university for banning rugby club barbecues, exhaust from motor vehicles or indigenous smoking ceremonies.

Where the ethics get interesting, though, is when the smoking argument shifts from harm-to-others to amenity, or "I don't like it" arguments. I was comfortable with supporting smoke-free outdoor coffee tables, for the same reason I support outdoor stadium smoking bans. Someone smoking next to me while I eat lunch outdoors is not going to really harm me, but the imposition is unpleasant in the same way as loud music away from music venues or dog faeces underfoot.

Some of my colleagues believe that it's OK to ban smoking in public spaces because it denormalises smoking by driving it out of sight. Some argued at my university that banning smoking altogether would promote non-smoking as the norm and that we should all feel comfortable with coercing smokers to stop smoking publicly, to set a good example to children. The government's ban on smoking on suburban playing fields and playgrounds, and the long-standing ban on smoking by teachers on school premises, are all about reducing adverse role-modelling.