The air in Silver Bay must continue to meet a three-decade-old “control city” monitoring standard comparing it with the air quality in St. Paul. The Minnesota Pollution Control Agency (MPCA) does not have to complete an Environmental Assessment Worksheet (EAW) before it processes Northshore Mining Company’s August 2008 application to remove that standard from Northshore’s air emissions permit after an April 12 dismissal by the state Court of Appeals of an appeal filed by the MPCA.