Des Moines Register: A Dutch chemical company has reached an agreement with the U.S. Environmental Protection Agency to invest $50 million in six U.S. manufacturing plants, including one in eastern Iowa, to resolve alleged state and federal clean air violations. The EPA said three LyondellBasell Industries U.S. subsidiaries have agreed to upgrade operations at six petrochemical manufacturing facilities. One is in Clinton and the others are in Texas. Lyondell also will pay a $3.4 million civil penalty.