Iowa’s counties scored among the worst -and- the best in the nation in a new E-P-A study of toxic chemicals in the air. Brian Button, an air quality specialist at the Iowa Department of Natural Resources, says the counties with high levels of pollution are generally those with high populations.While Button says Scott, Clinton, Johnson, Linn, Woodbury and Muscatine counties were listed for having high concentrations of certain toxic pollutants in the air, he says Iowa’s sparsely populated areas appeared to be much cleaner.Button says there’s no need for anyone in the counties with high toxic concentrations to panic. He says this E-P-A study only covers chemicals in the air — it doesn’t yet go the next step of discussing exposures and long-term health risks. He says that information will be released in January.The list 32 of chemicals the E-P-A zeroed in on includes vinyl chloride, P-C-B’s, mercury and manganese.