The streets around the Dirksen Federal Courthouse were shut down for a little more than two hours this morning while emergency crews responded to a hazardous substance report.Spokesman Larry Langford of the Chicago Fire Department said a check of the air quality inside the courthouse and its basement as well as the subway showed the air quality was normal.Police and fire vehicles blocked off the streets around the courthouse at 219 S. Dearborn St.Yellow police tape and orange biohazard tape was strung outside the …