As first shown in 2003, the auxiliary function of carotenoids as quenchers of singlet oxygen contributes to the photoprotective role of OCP has also been demonstrated under strong orange-red light, which are conditions where OCP cannot be photoactivated for its energy-quenching role.  This is significant because all oxygenic phototrophs have a particular risk of oxidative damage initiated by singlet oxygen (O), which is produced when their own light-harvesting pigments act as photosensitizers.