What We Know About Insulation Materials

Though it is not always easy, careful consideration of insulation products can lead to improved tenant health through the use of safer choices. 


Worker installing insulation

Fiberglass* Fiberglass fibers can irritate the skin and respiratory system. Make sure the area is cleaned properly after installation. Health Threat: Low 

Mineral Wool Mineral wool fibers can irritate the skin and respiratory system. Products typically use formaldehyde as a binder, but manufacturers say it burns off during production. Check for air quality or VOC (volatile organic compound) certifications to ensure low or no off-gassing. Health Threat: Low

Cellulose Fibers can cause respiratory concerns. A small number of people are sensitive to fumes from the ink on the old newspapers and/or the borate used to treat the fibers for fire and pest prevention. Health Threat: Low

Natural Wool Some products contain borate flame retardants, which are now under review by the European Union and Canada. Health Threat: Low

Cotton  Dust can be a respiratory irritant. The insulation is treated with borate flame retardants, which are now under review by the European Union and Canada. Health Threat: Low

Spray Polyurethane Foam (SPF Foamed-in-Place) The chemical isocyanate found in SPF can cause cancer and asthma. Little is known about the toxicity of the fire retardant TCPP, however structural similarity to other flame retardants that are carcinogenic raises concerns. Special protection is needed for installation. The U.S. Environmental Protection Agency says “research” is needed on accurate curing, or drying, times for SPF as the thickness of application, temperature, and humidity can cause the product to off-gas for longer periods of time. Alternatives include cellulose, mineral wool, fiberglass, cotton, cementitious foam, and natural wool. Health Threat: Medium

Polyisocyanurate The rigid boardstock form of SPF, nearly all polyiso also contains the fire retardant TCPP, though one roofing product promotes that it is free of halogenated flame retardants. Health Threat: Medium

Polystyrene Foam (EPS or XPS Rigid Boardstock) The fire retardant HBCD contains bioaccumulation toxicants that build up in the environment and can cause reproductive and developmental problems, cancer, nervous system damage, and genetic impacts. There also is fear that styrene, which is suspected of being carcinogenic, could off-gas. Alternatives include cork, rigid mineral wool, rigid fiberglass, and cellular glass. Health Threat: High

* lightweight residential