Environmental considerations

Given the relative use of these two materials, mineral wool has, on average, 75 percent postindustrial recycled content. (Postindustrial recycling refers to the use of industrial by-products, as distin­guished from material that has been in consumer use.)16 According to the North American Insulation Manufacturers Association (NAIMA), over 938 million lb (425 million kg) of blast furnace slag was used in 1992 to produce slag wool.9