text: President Bush's EPA resisted listing carbon dioxide as an air pollutant on two grounds. The first was definitional. "Air pollution" is not defined in the statute, but under normal rules of construction it must mean something, and absent any other guidance the logical source of wisdom is a dictionary, which defines "pollute" as meaning "to make . . . impure or unclean." So a pollutant must be something that is not only emitted, but something that renders the air impure, which can hardly be said of carbon dioxide. Justice Antonin Scalia's dissent commented: "It follows that everything airborne, from Frisbees to flatulence, qualifies as an "air pollutant.' This reading of the statute defies common sense." Marlo Lewis of the Competitive Enterprise Institute (CEI) observes that any other interpretation also makes the "precursor" sentence redundant, because if everything emitted is an air pollutant, then precursors would be pollutants automatically. The Court brushed aside this perfectly conventional (and correct) argument from statutory interpretation, finding the statute "unambiguous" in its meaning that anything emitted is a pollutant. Since the EPA had already said that carbon dioxide contributes to climate change, which endangers public health and welfare, it had no choice but to put it on the regulatory agenda.