While one drywall board may look very much like another, some are made with naturally occurring gypsum, while others are made from coal-fired power plant waste. A recent report published by the Healthy Building Network notes that while it may seem counterintuitive to caution against recycled content in a high volume building material, not all material that is considered “recycled content” is created equal. Some recycled materials can contain legacy hazardous content from their prior use, and some - like synthetic or flue-gas desulfurization (FGD) gypsum, which is created from environmental control systems installed in the smokestacks of coal-fired power plants that capture particles from coal burning as they travel through the smokestack or flue - are industrial waste materials from other processes.

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