Nanomaterial development and application are viewed as an emerging discipline, but exposure to, and work with materials in the nanoscale has been occurring for centuries. Engineered nanomaterials are heralded for their important, unique characteristics not exhibited by macroscale materials of the same composition. Exposure to nanomaterials presents a unique set of exposure pathways with potentially new benefits and risks. Since the early research with ultrafine particles, new commercial and residential uses of a wide range of nanomaterials are challenging our understanding of the impact of these materials on human health and the environment throughout their lifecycle.