You probably don’t want to snort titanium dioxide, no matter how much you think it looks like cocaine. On the other hand, various industries rely on the stuff: it’s a major pigment, a common component of sunscreens, and Hollywood’s favorite fake snow.
And when you mix it with concrete, the air over your roads gets a smidgen cleaner:
According to Eindhoven University of Technology, a roadway made of concrete blended with titanium dioxide can effectively remove up to 45 percent of the nitrogen oxides that it comes in contact with. The titanium dioxide, a photocatalytic material, captures airborne nitrogen oxides and, with the aid of the sun, converts it to nitrates that are harmlessly washed away by the rain.
The conventional three-way catalytic converter produces a substantial reduction in NOx emissions, provided everything is working correctly. Often it isn’t. (Drivers are often reluctant to make repairs, simply because of the cost.) While the concrete/TiO2 combination costs about 50 percent more than ordinary concrete, the cost of materials is a relatively small portion of the cost of building a road; the University says that a road using TiO2 will cost about 10 percent more to build.
And yes, apparently you can use it with asphalt.