ISO 4892.3-2016 is an international standard on methods of exposing plastics to light sources in laboratories, with a focus on the use of fluorescent UV lamps. This standard aims to simulate the efflorescences of materials when exposed to global solar radiation in a real use environment or through window Glass. The aging performance of materials is assessed by exposing samples to Fluorescent Ultraviolet radiation in combination with controlled temperature, Humidity and water mass. The 4th revision adds information on the combination of off lamps, improving the detail and accuracy of testing. ISO 4892.3-2016 applies to a wide range of plastic materials to assess their weathering performance under long-term exposure.