Fiberboard Ductwork

Has anyone experienced any problems with homeowners becoming ill due to fiberboard ductwork? I performed an inspection for a homeowner and every time they turn the HVAC system on, they become ill. I have found information that explains this type of ducting system can produce off gases of fiberglass and formaldehyde, and is more susceptible to mold due to moisture becoming trapped inside the insulation. Any advice I could give these homeowners would be greatly appreciated.

Thank you,

I am not aware of specific problems with fiber glass duct board been used for a long time but anything is possible especially if excessive moisture is introduced there probaly would be enough dust/dirt to support mold growth. Need to test for specific type of growth if any.