The cause of death of two Transco Railcar workers who died inside a tank car in Oelwein Thursday afternoon has been determined. The autopsy confirms the men breathed in nitrogen gas. The Fayette County Sheriff’s Office says the State Medical Examiner released preliminary findings on 46-year-old Daniel Steil and 49-year-old John Woodson. The men collapsed inside a tank car owned by A-D-M. A-D-M says nitrogen is sprayed inside railcars to prevent oxygen from getting inside and spoiling the products carried by the cars. The incident remains under investigation.