The country has made incredible progress over the last few decades in drastically reducing the six most common air pollutants. But that hasn’t stopped the EPA from using bad science to push costly new regulations in an attempt to remove a few more parts per billion (ppb) of particulates from the atmosphere—even if those pollutants naturally occur in certain regions at higher levels.

Take ozone, for example. Environmental activists have sued to force the EPA to impose new ozone limits soon and the EPA is expected to lower the allowable concentration of ozone from the current 75 ppb (parts per billion) rate to between 60 and 70 ppb. (Despite the fact that the agency deemed, and a federal court agreed, 75 ppb safe as recently as 2008.) But such a stringent new standard verges on the ozone levels that already occur naturally in the atmosphere. Ozone exists at 71 ppb at Big Bend National Park in Texas, for example, where there is no man-made pollution.

What’s worse, the EPA is using bad science to justify these new stringent standards. The overwhelming scientific evidence – hundreds of scientific studies – say ozone is safe at 75 ppb and no further health benefits will accrue with a more stringent standard. But the EPA refuses to evaluate all the scientific studies – called a “weight-of-evidence” analysis. This allows it to cherry-pick studies that confirm its position and ignore ones that do not.

Drs. Sonja Sax and Julie Goodman, of the Harvard School of Public Health criticize EPA ozone science further. They call out the EPA for not adequately controlling for smoking or participants’ health problems in its ozone studies. This results in biased conclusions that indicate ozone causes more health problems than what robust science supports. They also say the EPA’s science is flawed because it uses unrealistic expectations that undermine its results:

The EPA considers worst-case scenarios arguably to protect the most sensitive people in a population. However, in its ozone health-risk and exposure assessment, the EPA makes many “worst-case” assumptions that could not all occur at one time, leading to an unrealistic scenario that overestimates risks.

What’s even worse is that the agency’s failing science is expected to fuel one of the most costly regulations in history—the EPA itself estimates that such a standard could cost the economy up to $90 billion annually.