The Dirty Details
Properly installed insulation is critical for making your home energy efficient, as it can reduce the amount of energy lost when heating and cooling your home. There is no one best choice of insulation, but a number of better choices are available. The choice of insulation for your home project will depend greatly on the size of the space you are insulating and the climate in which you live. Keep in mind that some natural materials may be predisposed to moisture problems and, if you follow precautions, some traditional materials may also be good choices.
Insulation can be made from natural or synthetic fibers, and comes in several forms: batts, rolls, blown in, rigid boards or spray foam. But some types of insulation may contain toxic chemical flame retardants, formaldehyde and volatile organic compounds, or VOCs—all of which pose health risks.
The following types should be avoided:
Polyurethane Spray Foam Insulation
This type of foam contains harmful chemicals and can be especially hazardous for workers during installation. Watch out for spray foam containing a chemical known as methylene diphenyl diisocyanate, or MDI, which can cause asthma and lung damage in exposed workers. Spray foam can also contain the toxic flame retardant TCPP. If mistakes are made during installation, sprayed-on insulation foam is difficult to remove. For these reasons, EWG does not recommend this type of insulation, although it is highly effective.
Rigid Foam with Flame Retardants
Most rigid polystyrene foam insulation boards, both the EPS and XPS types, contain the toxic flame retardant HBCD, which was banned by the European Union in 2015. According to the Environmental Protection Agency, HBCD is a potential health hazard to humans based on its reproductive, developmental and neurological effects on animals. This chemical is especially hazardous during manufacturing and disposal. In addition to containing dangerous flame retardants, this type of insulation is made from petroleum chemicals.
Some XPS insulation is manufactured with butadiene styrene brominated copolymer, an alternative to the flame retardant HBCD. This copolymer was found by the EPA to have lower environmental and health hazards compared to HBCD in the use phase, but production and disposal issues remain with another brominated chemical.
Another type of rigid foam insulation—made with polyisocyanurate—does not contain halogenated flame retardants, but still uses organophosphorus flame retardants bonded to the plastic.
Asbestos in Insulation
Until the mid-1970s, insulation often used asbestos, which is now known to cause deadly diseases at even the lowest exposure levels. Although asbestos has been phased out of most home insulation, it has not been banned in the U.S. and some insulation boards currently on the market still contain asbestos. If you have asbestos in your home, or suspect you do, see the recommendations in EWG’s Consumer's Guide to Asbestos.
Use with caution:
Fiberglass—one of the most common types of insulation—used to contain formaldehyde binding agents, which have mostly been phased out. But some forms of mineral-wool fiber insulation may still contain as much as 5 percent formaldehyde. The fibers from these forms of insulation pose inhalation risks, particularly during installation. But spray-applied fiberglass does not contain flame retardants and typically has an inert binder.