How Smog Eating Buildings Are Clearing the Air

The next green building technology: cement that neutralizes pollution.

There are buildings that can harness the power of the sun, sway along with high winds and shake to the rhythm of earthquakes. Now there are at least a few that can eat smog.

Nemesi & Partners, the design team behind Palazzo Italia, the first smog-eating structure in the world, unveiled the building at the 2015 Milan Expo. Palazzo Italia is sustainable and uses solar power to achieve a status close to net zero energy, but the big draw is its façade. Made of a patented mixture of cement and titanium dioxide known as TioCem with TX Active, it absorbs nitrogen-oxide pollution in the air and converts it, by way of sunlight, to an innocuous salt that can be washed away by rain.

For cities like Mexico City, where pollution is bad enough that residents sometimes wear masks, pollution-fighting façades could be a game changer. A hospital in that city has already put one to use.

The exterior of the Torre de Especialidades medical building features mass-produced modules, known as prosolve370e, that are coated with titanium dioxide. The creators of the modules, Elegant Embellishments, estimated that the 100-yard smog-eating façade would be able to capture pollutants equivalent to the emissions of 1,000 cars. The decorative modules use plastic panels as their base.

Going back to cement with titanium dioxide mixed in — known as photocatalytic cement — perhaps the most exciting possibility is that it can also be used in other applications such as sidewalks, roofing, roads and concrete sound buffers.

The United States has been slow to embrace it, but a bike lane and sidewalks on one street in an industrial Chicago neighborhood used it back in 2012. The street, which also incorporated other “green features,” was dubbed “The Greenest Street in America.”  

Will more smog-eating streets and buildings follow? Time will tell.