1 January 2021 deadline approaching for IMO NOx Tier III


In recent years maritime environmental matters have been under increasing global scrutiny, most likely due to mounting fears surrounding climate change.  In a series of brief news bulletins, Justin Turner and I will be focusing on some current news updates illustrating the steps being taken by the maritime industry to tackle pollution and gas emissions from ships.

Background – MARPOL Annex VI and IMO NOx Tier III

Nitrogen Oxide (“NOx”) is one of the gaseous pollutants generated by ships that falls under the regulations of MARPOL Annex VI.  Annex VI sets limits on nitrogen oxide (and sulphur oxide (“SOx”)) emissions from ship exhausts and prohibits deliberate emissions of o-zone depleting substances.

Three tiers of NOx emission limits have been set for diesel engines with a power output higher than 130 kW with each Tier limiting the NOx emission to a value based on engine speed, depending upon the date of construction of the relevant vessel. These tiers are known as:  NOx Tier I; NOx Tier II; and NOx Tier III.   For NOx Tier III emission standards, Annex VI Regulations establishes certain NOx Emission Control Areas (“NECAs”).

Annex VI Regulations for the Prevention of Air Pollution from Ships establishes certain SOx Emission Control Areas (“ECAs”) with more stringent controls on sulphur emissions, however,  1 January 2020 was a key date for the rest of the world (i.e. outside ECAs), when the limit for sulphur in fuel oil used on board ships operating outside designated emission control areas was reduced to 0.50% m/m (mass by mass). 

Highlight:      1 January 2021 deadline draws closer for IMO Tier III NOx

NOx Tier III emissions standards are applicable only in NECAs. Currently, this means that NOx Tier III limits apply to ships larger than 24m and 500GT, with diesel engines larger than 130kw, constructed (i.e, keel laid) after 1 January 2016, in North American and US Caribbean ECAs.

However, during MEPC 71 in July 2017, the IMO adopted Resolution MEPC.286(71), amendments to MARPOL Annex VI, introducing two new NECAs – the North Sea and the Baltic Sea.  Therefore, from 1 January 2021, NOx Tier III limits will therefore also apply to ships built or operating in the Baltic Sea and the North Sea.  Furthermore, from this date, all recreational vessels built or operating in NECAs below 500GT built from this date shall have to comply with IMO Tier III standards.

The effect of this is that, in order to comply with the more stringent Tier III requirements, many more ships shall have to be installed or retrofitted with equipment/systems which can reduce NOx below the Tier III standards.


This issue is generating particular interest in the superyacht sector as, from 1 January 2021, IMO Tier III regulations will apply to all recreational vessels below 500GT built from this date.  Previously, vessels of less than 500GT of 24 metres or over in length, which has been specifically designed and is used solely for recreational use were exempt from IMO Tier III requirements.

It should be noted that these regulations also apply to yachts currently undergoing a refit where an engine is replaced by a new one. All things considered, there will be some many new challenges faced by the yacht industry as a result of these regulations coming in to effect next year, not least the probable need for bigger engine rooms to accommodate SCR (Selective Catalytic Reduction) systems, the resulting effects from additional weight, including increased fuel consumption, and so on.  



*This publication is provided for your convenience and does not constitute legal advice. This publication is protected by copyright. © 2020 Hannaford Turner LLP

Share this post

Facebook Tweet Linkedin Email