MODEL RELEASED. Ultraviolet monitor. Scientist uses a light source to calibrate a spectrometer that detects Ultraviolet (UV) rays in sunlight. The spectrometer measures the UV intensity at different wavelengths. UV is the component of sunlight which causes sunburn and skin cancers. It is mostly blocked by the atmosphere, particularly by the gas ozone. As ozone levels fall due to pollution, UV levels are predicted to increase. Photographed at the Mauna Loa Observatory in Hawaii, USA. Due to the intense tropical sunshine and the high altitude, Mauna Loa has the highest recorded UV levels in the world.