Designing for safe demolition - the hazard potential of nanomaterials

When specifying products, designers should consider the health and safety of those working with the materials, either during construction or during decommissioning and demolition of a building or facility at the end of its life. The use of nanomaterials (those with at least one dimension less than 100 nm) in construction is reported to be on the increase, but it is difficult to identify exactly which products contain them; and there are uncertainties regarding their hazard potential. This paper is based on an ongoing IOSH-sponsored study to catalogue nano-enabled construction products through review of the literature, and consideration of manufacturers' data; and interviews with construction professionals to assess how widely they are used. The study is also using material characterisation techniques to identify the nanomaterials involved and assess the potential for particle release from products at end of life. The study has found wide variation in the hazard profiles of the different materials and products currently available. Some specialist concretes for example, are enhanced with silica fume which has been widely used for around 40 years and is a relatively low-risk nanomaterial. Other forms of nanosilica are used in insulation materials and surface coatings. Carbon nanotubes (CNT) are a nanomaterial which are hazardous in some forms. CNTs are not yet used commercially in concrete but are forecast to appear in the marketplace in a limited capacity by 2016. They are also used in very specialised surface coatings. Further information is needed to assess whether they could pose a health risk at end-of life from the combined impacts of material degradation over time and the destructive techniques commonly applied in building demolition and recycling (e.g. crushing, cutting, drilling etc).