Good Idea: Smog-Eating Cement

From the New York Times Magazine 12/09/2007

The cement’s chemical composition is enhanced with titanium dioxide, which under the right conditions can neutralize some harmful pollutants. When exposed to sunlight or ultraviolet light, the titanium dioxide is “activated,” Borgarello says, and pollutants that come in contact with the surface of the cement are oxidized. Hazardous nitrogen oxides and sulfur oxides, for example, are transformed into harmless nitrates or sulfates, which simply rinse off the building with rainwater. This also keeps it especially clean.

A small step but a step nonetheless.