Photocatalytic air treatment

A photocatalytic reactor comprising:

• a reaction chamber arranged to receive an airflow comprising one or more airborne contaminants, the reaction chamber comprising:
• a first set of fins, a second set of fins, a photo-catalyst for photocatalytic degradation of one or more of the contaminants disposed upon at least one face of each fin, and a light source arranged to illuminate at least a portion of the photo-catalyst disposed on each fin in order to facilitate photocatalytic degradation;
• wherein each of the first set of fins is arranged such that a line extending from a base of the fin through a free end tip of the fin is directed to a first convergence point located within the reaction chamber;
• wherein each of the second set of fins is arranged such that a line extending from a base of the fin through a free end tip of the fin is directed to a second convergence point located within the reaction chamber;
• and
• wherein the first convergence point is different to the second convergence point, and both the first convergence point and the second convergence point are offset relative to a position of the light source.