When you think about air pollution in cities, you usually think of traffic congestion or smokestack emissions. But for a novel concrete firm in Italy, the answer to smog may lie in reformulating the cement used in building construction. Yes, believe it or not, the European firm Italcemente has created a smog-eating cement that contains titanium dioxide, which in the presence of sunlight acts as a photocatalyzer, and can decompose pollutants like sulfur oxides and ozone. Studies indicate that if just 15 percent of the surface area of Milan, Italy, were covered with this novel cement, air pollutants there could be reduced by a hefty 50 percent!