Depending on what the insulation type is and it’s age, this flexible ductwork could create health problems. The ductwork insulation material may be glass fiber or another product such as asbestos containing material. The only way to tell for sure is to have a certified public or industrial health lab test a sample to determine if it is glass fiber, asbestos, or another product. Before taking a sample of the material yourself, to avoid generating a hazard, contact the a …