How to tally up the benefits from EPA’s mercury rule

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How to tally up the benefits from EPA’s mercury rule:

On Tuesday, the Environmental Protection Agency threw back the curtain on its big new regulation to limit mercury emissions and other toxic pollution from coal-fired power plants. As David Roberts writes, this is potentially a very big deal from a public-health perspective, as the rule is expected to “save tens of thousands of lives every year and prevent birth defects, learning disabilities, and respiratory diseases.”

Indeed, the EPA estimates that the regulation will produce $37 billion to $90 billion in health benefits by 2016 (compared with clean-up costs of about $11 billion). Confusingly, though, most of these estimated benefits don’t actually come from reducing mercury pollution. So where do they come from? And just how big a deal are these rules?

First, some background. There’s plenty of evidence that mercury — a neurotoxin — inflicts quite a bit of harm on the public, especially in poorer, high-pollution locales. A 2005 study in the journal Environmental Health Perspectives, for instance, looked at the effects of mercury poisoning on the brains of fetuses. It found that 637,000 babies were born each year with hefty amounts of mercury in their bloodstream, with about two-thirds of those kids suffering IQ loss. The authors estimated that the lost economic productivity due to decreased intelligence came to about $8.7 billion per year, with $1.3 billion of that caused by power-plant damage.

Oddly enough, though, when the EPA calculated benefits from its new pollution rule, mercury only played a small role. A large chunk of that estimated $37 billion to $90 billion in benefits is due to a reduction in premature deaths — about 11,000 per year by 2016 — thanks to a reduction in particulate matter, not mercury. As utilities install scrubbers at coal plants to sop up mercury, they also end up curbing other types of pollutants, and those co-benefits account for the vast majority of the stated benefits. (Indeed, former Bush administration regulatory czar Susan Dudley criticized the rules on this front.)

Now, that doesn’t mean the EPA isn’t cleaning up mercury, or that the mercury benefits are worthless. What it means is that it’s easier to put a hard number on the benefits from cleaning up particulate pollution — by totaling up the dollar value of lives saved — than it is to calculate the full value of, say, avoiding cognitive damage in young children. Scientists are still struggling to quantify the damage wreaked by mercury. And, as Michael Livermore writes, the EPA didn’t put a dollar value on various benefits from the regulation, like reducing mercury in store-bought fish, because it was too murky. The benefits may be there, but they’re not factored in.

Meanwhile, the rule will produce other side benefits that aren’t accounted for in the headline figures. For instance, the rule is expected to hasten the retirement of roughly one-tenth of the nation’s coal-fired power plants, mostly the oldest and dirtiest, which kick up plenty of heat-trapping carbon dioxide into the atmosphere. If you assume that the social cost of emitting carbon dioxide is at least $10 per ton (the average of peer-reviewed studies in the IPCC’s 2007 review, although many studies had a far higher figure), then this is a huge benefit indeed. But it’s left out of the EPA’s estimates.

So there’s little question that the EPA’s new mercury regulations are a huge deal. But there's plenty of room to argue over the true value of the rules.