The New Source Review (NSR) provisions of the Clean Air Act prohibit companies from expanding their oil refineries or other facilities in a way that increases pollution unless they apply for a permit and put on best available pollution controls. The Bush Administration wants to exempt companies from this requirement if emissions resulting from plant modifications do not rise above a plant’s worst emission levels out of the last ten years. The Bush Administration insists that its loophole will not increase emissions, as common sense would otherwise dictate. The Administration also claims that it is impossible to quantify pollution increases under its plan and has challenged the environmental community to provide this analysis. We took the challenge and found that pollution would in fact increase under the Administration’s proposal.