UFFI

UFFI was the material used in the 1970s and early 1980s to insulate older homes. The material was injected between the studs in the wall cavity by drilling holes on the exterior and/or interior walls between each stud, and above and below windows and doors. The material was mixed on-site (formaldehyde was used as a binder) and pumped into the cavity where it expanded into foam, dried, and became relatively rigid. It is found adjacent to electrical outlets and switches and at the stud bays and wood plates of older balloon-framed houses. The foam is fragile and will break up, almost to the consistency of baby powder when you check it. 

The insulation was considered an ideal retro fit insulation with good insulation qualities.  However, the material, once installed, would off-gas and cause an allergic reaction and respiratory problems in some people.

The material was banned in the United States in 1982 by the Consumer Product Safety Commission.  In 1983, the ban in the United States was overturned by the U.S. Court of Appeals.  The off-gassing of formaldehyde occurred over a 5 to 10-year period. The off-gassing period and severity is affected by the relative humidity, the exposure to the sun and the ability for the humidity to access the walls. Since the material has not been installed since the early 1980s, the hazards associated with the off-gassing of the material are considered to be negligible.