The ASTM D4364-2022 standard specifies a method for outdoor accelerated aging testing of plastics using concentrated natural light. The method focuses sunlight on the specimen by using a flat mirror system to simulate natural exposure under different climate conditions. The standard describes accelerated test conditions for both non-hydrocyclic and programmed hydrocyclic and emphasizes the effectiveness of UV radiation during testing. Because of changes in the natural environment, test results may differ from the effect of actual natural exposure, so predicting actual life with accelerated test results is not recommended. The standard applies to a wide variety of plastic materials, including films and sheets. Users need to focus on safety practices and determine regulatory applicability.