It sounds too good to be true. But a company claims to have created a smog-eating material that can be used to clad buildings. US-based Alcoa, the world’s largest aluminium company, has created an air-cleaning surface called Reynobond which eats organic material either stuck to it or floating near it. The technology relies on the reaction caused when sunlight strikes titanium dioxide to excite electrons, which in turn transfers energy to water in the air to form free radicals OH (hydroxyl radicals) and O2 (superoxide anions). These free radicals are both powerful oxidisers that can attack any organic material either on the panel’s surface or floating by. The material actively works to remove pollutants by using sunlight, water vapour, and oxygen in the air to clean the air itself. In fact, 1000sqm / 10,000sq ft² of it on a building can have approximately enough cleansing power to offset the smog created by the pollution output of four cars every day, which is the approximate air cleansing power of 80 trees.