Officers in Charge, Marine Inspection, affected companies, and Recognized Organizations that issue International Air Pollution Prevention certificates on behalf of the United States are encouraged to apply this Work Instruction as it relates to the installation and certification of “qualifying engines” that are required to meet IMO Tier III performance standards.
Source: USCG
Link: 10/29/2018: New work instruction on enforcement of MARPOL Annex VI Regulation, engine operation in Emission Control Areas