2.1 Nanoparticles in the Atmosphere
In the previous chapter, the special properties of pieces of matter with nanoscale dimensions were presented and how this novel behavior could be exploited in technologies as diverse as advanced engineering materials and health care. This chapter is about naturally occurring nanoparticles, both in our immediate environment—that is, the Earth's crust, oceans, and atmosphere—and out into deep space, where nanoparticles with their unique properties have helped shape the observable universe. The particles in the Earth's atmosphere have an important influence on the climate but also have a poorly understood effect on life and our health. Improving our understanding of the effect of airborne nanoparticles is becoming increasingly important in a world where nanotechnology is poised to become a major activity. Clearly, the amount of manufactured nanoparticles will increase, so it is wise to be aware of how they interact with life and with the environment. It is important to emphasize, however, that manufactured nanoparticles are normally bound up in some material and that the number of “loose” particles produced by nanotechnology will not necessarily become significant compared to those produced by the natural processes described below. In this chapter the discussion is extended to encompass nanoparticles that are generated by existing human activities not directly involving nanotechnology, such as power generation, ...