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Read Part 1 of this series: Losing their health and homes to spray polyurethane foam.
Spray polyurethane foam is widely promoted as a green building material for its ability to improve energy efficiency. It insulates better per inch than fiberglass or cellulose, which can mean major energy saving on heating and cooling. However, energy efficiency isn't the only consideration when it comes to sustainable building. A closer look at spray foam's chemical makeup reveals a number of substances that are known to be hazardous.
Spray polyurethane foam consists of two liquid chemical components, referred to as "Side A" and "Side B," that are mixed at the site of installation. Side A is mostly made up of isocyanates, while Side B usually contains polyol, flame retardants and amine catalysts. These chemicals create hazardous fumes during the application, which is why installers and nearby workers should wear personal protective gear during this process. Once the foam has fully expanded and dried, manufacturers say it is inert. If the chemicals are not properly mixed, they may not react fully and can remain toxic.