Statistics show that absolutely 100% of people who sit near a campfire or breathe in smoke from another's campfire will eventually die.
In all seriousness though, outside of those segments of the population that are exposed to smoke/ash on a highly regular basis and/or those that are unusually susceptible to breathing problems (like those with chronic asthma), I have a hard time believing that occasional exposure to wood smoke/ash should rank high on one's health risk radar.
I understand and can appreciate that smoke is unhealthy and even exposure to a little of it isn't doing your lungs, eyes, throat, etc. any favors, but to conclude that wood fires pose such an unacceptably high health risk that all should avoid fires entirely seems like a bit of an overreaction. Like any other potentially dangerous activity or commodity, a little care and moderation should go a long way toward helping avoid, or at least minimize, the ill effects of smoke/ash (like only sitting around the occasional campfire and trying to stay upwind of it).
Interestingly, Southern CA beach cities are caught up in the midst of this debate right now. The City of Newport Beach is attempting to remove all of the public fire rings from City beaches. Apparently, homeowners along the beach front in these areas are complaining of being inundated with smoke and ash from these fire pits, especially during the busy summer season. Others charge the effort to remove the fire pits is a thinly veiled attempt at dissuading out-of-town beachgoers from using these beaches by taking away these popular amenities. The City failed to get the approval from the CA Coastal Commission on their first attempt to remove the fire pits, as the Commission saw the removal of the fire pits as a loss of "public coastal access/recreation." Since then the regional Air Quality Control Board has decided to step into the fray and proposed a rule change that would require the removal of all fire pits from all beaches within their jurisdiction under the guise of air quality and public health. This, of course, has kicked off a sh!tstorm of opposition from folks who enjoy the fire pits as well as other coastal cities who enjoy the added traffic and revenue the beachgoers bring to their City. Not to mention, it's caused others to question the prioritizing of beach fire pit removals over other much larger sources of smoke/ash (e.g. wood burning fireplaces in many homes). Not sure where this will all end up when all's said and done. Wouldn't be surprised if the heavy hitter politicos have to step in to settle the dispute.