This document discusses how nanotechnology can be used to detect, clean up, and prevent air pollution. It describes various air pollutants and their health impacts. Nanotechnology enables sensing of pollutants using portable sensors. It can also purify air through photocatalysts that use light to oxidize pollutants, and nanofilters such as nanofiber membranes coated with silver nanoparticles that capture bacteria. Additional applications include using nanocatalysts to break down volatile organic compounds and convert carbon dioxide to other usable substances.