Complex sentence: The toxic substance apparently originated from dust emitted by the Cemex Cement plant in Davenport, as the levels of Chromium VI measured eight times the air district's acceptable level at Pacific Elementary School and 10 times at the Davenport Fire Department.
Split into simpler sentences: The toxic substance apparently originated from dust emitted by the Cemex Cement plant in Davenport. The levels of chromium 6 measured eight times the air district's acceptable level at Pacific Elementary School and 10 times at the Davenport Fire Department.