The NOxBOX noise and emission barrier is an evolution of Larix’s proven StoneBOX model. It consists of untreated larch heartwood filled with lava stones. With a special process, the lava stones are coated with titanium dioxide prior to installation. The titanium dioxide layer is what creates the sound barrier, but also carries a new function: the titanium dioxide filters pollutants from the air. Nitrogen oxides are reduced via a chemical reaction with the air, using the titanium dioxide as a catalyst. The NOxBOX filters air passing through the wall of up to 60% of particulate matter (PM) and up to 40% of nitrogen oxides. Fine dust and soot particles are tightly bound in the numerous cavities, after which the wall can be easily hosed down with water for effective maintentance. A patented fish-mouth principle provides for greater air circulation around and into the wall, which further increases the absorption of dust and nitrogen oxides. In addition, the structure is well-suited to be f