Apparently, you can capture nitrogen dioxide (NOx) floating around and make the air cleaner if you coat a billboard with a titanium dioxide coated vinyl.
Toyota is trialing the idea in Los Angeles and San Francisco in a bid to further promote the cleanliness of the Mirai Fuel Cell – the Japanese manufacturer will have 37 ads in early April covering a total of 24,960 square feet in the two cities. That’s enough to do some “scrubbing” – the equivalent NOx emissions of 5,285 vehicles each month, according to the company. The automaker has went even further – wrapping one of the Mirais with titanium dioxide coated vinyl at the first Environmental Media Association Impact Summit in Beverly Hills.
Using titanium dioxide on surfaces exposed to the elements to capture NOx is actually a well-known method – according to a 2008 Lawrence Berkeley National Laboratory report the “use of titanium dioxide nanoparticles in building materials, and on roads, freeway sound walls, and so forth, is proposed by” proponents of the technology for some time. Titanium dioxide (TiO2) is used in things like toothpaste and white paint and “the reaction between the titanium dioxide, ultraviolet light and water vapor transforms the airborne NOx into a nitrate that while perhaps is not ecologically neutral certainly is better for air quality.” The billboards will actually stay up for a limited amount of time – until the end of May.