Recently I've read that blog post by Sam Harris and I was quite shocked. I don't have a fireplace or any habit related to a systematic wood-burning. But is wood smoke really that bad as it is described in the text? Is there a general medical/scientific consensus about it? Can I have some more references on the topic?
Finally -- should I, say, conclude that it would be better for my health to avoid hanging around campfires and/or barbecues?
You need to look no further than the (single) reference this blogger gives at the bottom of his post. His link is behind a pay-wall, but a google search leads you to a pre-print draft posted by one of the reference's original authors.
The article is a review of scores of other studies, and perhaps the original authors said it best (in the Conclusion):
...we conclude that although there is a large and growing body of evidence linking exposure to wood/biomass smoke itself with both acute and chronic illness, there is insufficient evidence at present to support regulating it separately from its individual components, especially fine particulate matter. In addition, there is insufficient evidence at present to conclude that woodsmoke particles are significantly less or more damaging to health than general ambient fine particles. Nevertheless, given the importance of woodsmoke as a contributor to particle concentrations in many locations, strategies to reduce woodsmoke emissions may be an effective means of lowering particle exposures. In addition, given the weight of toxicologic evidence, additional epidemiologic studies are needed to confirm our conclusions.
With the above in mind, it would seem that the original blogger overstated his case a bit, in a provocative manner, when he said things like:
[Wood smoke] is at least as bad for you as cigarette smoke, and probably much worse.
and
The case against burning wood is every bit as clear as the case against smoking cigarettes. Indeed, it is even clearer, because when you light a fire, you needlessly poison the air that everyone around you for miles must breathe.
It should be no surprise that breathing wood smoke is bad for you. The question would seem to be "how bad is it?", and while the blogger paints a picture of global disaster/catastrophe, the scientific research is far more tentative (right now, at least).
The smoke wood burning can be bad for health but most of the damage occurs when done indoors in poorly designed dwellings
As this letter from the BMJ summarises:
Globally however, human exposure to particulate matter (PM) in terms of the number of people, exposure intensity and time spent exposed varies greatly in different parts of the world. Only 1% of global PM exposure occurs in outdoor environments in the developed world with a further 9% occurring indoors in the developed world. 14% occurs outdoors in the developing world while a staggering 77% of human exposure to PM occurs in indoor environments in the developing world
Almost one-half of the world’s population burns organic material such as wood, dung or charcoal for cooking, heating and lighting. This form of energy is associated with very high levels of indoor pollution and an increased incidence of respiratory infections, including tuberculosis, COPD and cataracts to name a few. The World Health Organization lists indoor air pollution from burning solid fuels as one of the top ten global health risks, responsible for 1.6 million premature deaths per year and 2.7% of the global burden of disease.
The source for some of these numbers is a WHO publication Fuel for life: household energy and health (full text as pdf here).
A simple summary would be that most of the damage from burning wood occurs when done in poorly ventilated indoor environments. Standing around an open air bonfire is probably not a big risk in comparison.
