text: Light2CAT was a project funded by the European Commission from 2012 to 2015. It aimed to develop a modified  that can absorb visible light and include this modified  into construction concrete. The  degrades harmful pollutants such as NOx into NO. The modified TiO is in use in Copenhagen and Holbæk, Denmark, and Valencia, Spain. This “self-cleaning” concrete led to a 5-20% reduction in NOx over the course of a year.