The basic logic behind a cap-and-trade system or carbon tax is to put a price on one of the major hidden costs, or externalities, created by fossil-fuel use: namely, the greenhouse-gas emissions that are causing climate change. But global warming isn't the only hidden cost of our fossil-fuel economy. There are also the health impacts from air pollution. The devastation caused by mountaintop-removal mining in Appalachia. Arguably, the military costs involved with maintaining a presence in the Middle East. And now, via Science Daily, a new study in the Journal of the American Medical Association tries to pinpoint yet another externality of fossil fuels�workplace safety.

The study, by Steven Summer and Peter Layde at the Medical College of Wisconsin, examined the full life-cycle of energy production�from extraction to generation to distribution�and found that a shift away from fossil fuels and toward renewable energy over the next decade could potentially avoid some 1,300 worker deaths and measurably improve health and safety for up to 700,000 workers in the United States. That's largely because oil, coal, and gas mining is currently the second-most hazardous occupation around, with some 27.5 workplace deaths per 100,000 (compared with an economy-wide average of 3.4 deaths). This includes injuries from extraction, as well as exposure to hazardous particles and gases.

On the flip side, renewable industry is hardly risk-free. Solar photovoltaic production involves a fair amount of toxic air pollution, and of course it can be dangerous to assemble large, hulking wind turbines. But all told, the health and safety advantages of renewablse are pretty stark. (Though, curiously, one of the major sources of death in fossil-fuel production is highway crashes�drivers aren't subject to the same work-hour standards that truckers follow�and that won't necessarily change much with a move to wind and solar.) The one big exception? Biomass and ethanol production. As it happens, agriculture is even more hazardous than mining, with 28.7 deaths per 100,000, so moving to biofuels is actually a net negative for worker health.

Anyway, improved health and safety is clearly a net good, and one that doesn't ever get factored into those CBO studies tallying up the costs of climate legislation. But I do wonder, is it really right to call this an externality, as the authors do? A lot of those mining injuries and deaths, after all, will be reduced because the mining industry will shrink and at-risk workers will lose their jobs. The resulting clean-energy economy may well be safer and healthier overall�and that's good to note�but the transition won't be entirely painless.

(Flickr photo credit: Robert Pool's Glasgow Collection)

--Bradford Plumer