; and (2) an examination of the changes made by international operators to gas pipeline facilities to transport gas blends described in subsection (a) safely, including changes made to pipeline facilities in the United Kingdom, Canada, Europe, Australia, and Hong Kong. (c) Considerations In conducting the study under subsection (a), the Comptroller General shall consider— (1) changes that domestic and international operators of gas pipeline facilities have implemented to safely transport a gas blend described in subsection (a), including changes to odorants and leak-detection methods, pipeline materials, metering, and operational standards used by such operators to account for the operation and integrity of gas pipeline facilities; and (2) how such operators have taken into account the effect of transporting a gas blend described in subsection (a) on gas pipeline facility infrastructure, including— (A) gas pipeline facility materials, including cast iron, steel, composite pipe, and plastic pipe