Calvin Beisner, Cornwall Alliance: Pollutant, according to Mirriam-Webster’s, denotes “something that pollutes,” and to pollute is “to make physically impure or unclean” or “to contaminate (an environment) especially with man-made waste.” The Google online dictionary defines pollutant as “a substance that pollutes something, especially water or the atmosphere,” and pollute as to “contaminate (water, air, or a place) with harmful or poisonous substances.” Carbon dioxide isn’t harmful or poisonous except at concentrations over a hundred times higher than its concentration in Earth’s atmosphere—levels that we’ll never approach by burning fossil fuels.
