Recently, the impact of nanoparticles and nanomaterials on health and environmental effects has become a big issue. There are two types of nanoparticles to be considered in hygiene science; environmental nanopartcles emitted from automobiles and manufactured nanoparticles such as fullerenes, carbon nanobutbes, and ultrafine metals/metal oxides. These very fine particles are potentially health threatening, because they are supposed to be highly permeable in the lung and skin tissues and small enough to evade phagocytosis by reticuloendothelial system. The dose metrics are critical to evaluate toxicity of nanoparticles, because the surface-based rather than weight-based concentration has been reported to correlate well with effects and endopoints of nanoparticles. Research on environmental nanoparticles should be done as a part of research for fine particles or particulate materials less than 2.5 μm (PM2.5). Variety of materials, such as carbon, metals, and metal oxides, are included in manufactured nanoparticles. Moreover, some of manomaterials are generated in the shape of fiber and sheet. Thus, we should focus more on nano-specific biological interactions and tissue permeability to investigate health effects of manufactured nanoparticles. In this report trend in health effects of nanoparticles is overviewed.