When the Environmental Protection Agency (EPA) announced a new ground-level ozone standard of 70 parts per billion (ppb) on October 1st, it defended against criticism from all sides by saying its decision was based purely on science, untainted by economic considerations. As I argue in a new paper, however, that is simply not believable.

Science, though important, is rarely sufficient for making policy decisions for two reasons. First, while scientific information is essential for understanding questions of fact, it simply cannot make the ultimate decision regarding what policy should be. Second, when predicting health risk, scientists will never have complete information, so bureaucrats must make assumptions and judgments when interpreting scientific information for rulemaking.

And yet, the Clean Air Act does not recognize this. It requires EPA to examine the national ozone standard every five years and then base the decision of whether to revise it on science alone. No other considerations, including economic impact, may be taken into account.

When science is the only factor that can legally be considered in setting a standard, no one is immune to the temptation to put a spin on science to advance policy goals.

EPA presents its new ozone standard as if it were a magic number—exactly meeting the statutory requirement that it be “requisite to protect public health” with an “adequate margin of safety,” but going no further. It provides precise-sounding predictions of the health benefits to be achieved, but its pronouncements don’t admit to the considerable uncertainty about the actual risk, or its reliance on biased inferences and assumptions for handling that uncertainty.

Policy makers charged with making difficult policy decisions avoid responsibility by claiming their hands were tied by the science; and key policy choices, disguised as science, rest with unaccountable staff.

No one can seriously believe the Administration’s final ozone rule was not influenced by the intense pressure it faced from two opposing forces. On one side was its environmental base, urging a tighter standard as penance for the President’s 2011 decision to delay issuing the rule. On the other were businesses and communities concerned about the rule’s enormous economic impacts, who argued against any change to the existing standard. 

These are very real tradeoffs that deserve open and transparent debate, rather than the pretense that they can be made by considering only science.