CARB states that the smoke opacity test is a quick and inexpensive way to detect if an engine is emitting excessive emissions. CARB maintains that the smoke opacity test is technologically feasible and that compliance with the standards does not require the incorporation of any new technology not already required by existing regulations that have previously received an EPA authorization. CARB also states that the clarification of the Tier 4 FEL emission standards provisions are technologically feasible and were designed to correct an unintentional error and to clarify the original intent of the previously authorized CHE regulations. The CHE amendments only require retrofit to the Tier 4 emission level if appropriate technology is available and require the retrofit be performed within one year. EPA did not receive any comment or evidence to suggest that either of the two amendments for which CARB requested authorization is technologically infeasible.