This chapter discusses the emission, transformation, and fate of incidental airborne nanoparticles. It starts with the upâ€toâ€date summary of recent review articles covering various aspects of both the incidental nanoparticles and ENPs. Transformation processes play an important role in influencing the characteristics of nanoparticles both spatially and temporally. A common method to represent the atmospheric size distributions of atmospheric particles is through various modes. A typical size distribution in atmospheric environments shows the presence of the following modes:nucleation, Aitken, accumulation, and coarse. Nucleation mode particles are those generally formed by the gasâ€toâ€particle conversion after rapid cooling and dilution of exhaust emissions. Understanding the different transformation processes (i.e., nucleation, coagulation, condensation, evaporation, and dry deposition) is important in order to study the temporal and spatial changes occurring to nanoparticles in the atmospheric environment. The detection of ENP concentrations is necessary for determining human exposure in both the indoor factory environment and ambient nonâ€workplace atmosphere.
