Hard NOx

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.



  1. Nicole »

    10 July 2010 · 10:58 pm

    I had heard about this. Sounds like a great idea. Getting state DoTs to pony up another 10% may be difficult though, especially when they normally operate with lowest bidder winning. :)

  2. CGHill »

    10 July 2010 · 11:33 pm

    They’d done extensive lab testing beforehand; this is apparently the first time they set the stuff in an actual roadway.

    The unknown factor here is the new NO2 standard set by the EPA earlier this year. While the existing long-term average standard was not changed — it’s been in place since 1971 — a new short-term (one hour) standard is going into effect. So far, no one knows if they’re out of compliance yet. (There are no non-attainment areas for the long-term standard.) Once the numbers come in, though…

  3. Charles Pergiel »

    11 July 2010 · 2:00 am

    White asphalt? I don’t think I like the sound of that.

  4. Mark Alger »

    11 July 2010 · 8:31 am

    So lemme get this straight. We’ve spent all these billions of dollars on catalytic converters, jacked our engines around, added all that pollution to landfills, and all we had to do was add sunscreen to the roads?

    Or did I miss something?


  5. Mark Alger »

    11 July 2010 · 8:32 am

    Before somebody gets all serious and stuff up in my grill, I AM kidding.


  6. unimpressed »

    11 July 2010 · 10:00 am

    Mark, even with that disclaimer, SOMEONE will still get in your grill over it.

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