An accelerated aging investigation was performed on a variety of outdoor insulator materials. The materials were all commercial products fabricated using polymer bases including silicone rubber and EPDM. In this study the materials were subjected to synthetic acid rain solutions and aged on a tracking wheel. Matching samples were irradiated using ultraviolet radiation at different selected doses prior to acid rain exposure to determine combined weathering effects. Leakage current and surface wetting measurements were made for all samples throughout the aging period. The results of this study revealed that environmental exposure not only causes an increase in leakage current but also leads to irreversible surface degradation.