According to a university researcher I spoke with recently, polyurethane spray foam formulated for use in California is required to contain from 5 percent to 10 percent flame retardant by weight, and the size of the state’s market means that most other states get this same formulation. The researcher also claimed that flame retardants produce far more carbon monoxide and particulate smoke than untreated foam would, and are persistent and long-lasting in our bodies in an unburned state. Is it possible to avoid these problems by using foam without added fire retardants?

A.Rick Duncan, technical director of the Spray Polyurethane Foam Alliance (SPFA), responds: Like wood and many other building materials, foam plastic insulation is combustible and can give off particulate gases like carbon monoxide and hydrogen cyanide during a fire. At high concentrations, these gases pose an immediate threat to building...

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