The IMO issued a Circular forwarding guidance for port state control (PSC) under MARPOL Annex VI (air emissions). The goal is to provide international consistency in the conduct of PSC inspections, recognition of deficiencies, and application of control measures. Detainable deficiencies are identified as: (1) absence of a valid International Air Pollution Prevention (IAPP) Certificate or its equivalent; (2) a diesel engine with a power output of more than 130 kW installed or converted on or after 1 January 2000 that does not comply with the NOx Technical Code; (3) the sulphur content of any fuel being used on board exceeds 4.5% m/m; (4) non-compliance with relevant requirements while operating within a SOx emission control area…