Sulphur (Sox)

​Most ships use heavy fuel oil as fuel. Fuel oil has a relatively high sulphur content compared to other types of fuel, and the sulphur is emitted with the ship's exhaust gas in the form of sulphur dioxide (SO2), which is harmful to living organisms and can contribute to acid rain. Therefore, it is important to observe the permitted sulphur content limits.

The global upper limit for permitted sulphur content in fuel is 0,5 percent

In 2008, United Nations' International Maritime Organization (IMO) adopted MARPOL Annex VI, which regulates the sulphur content of ships' fuels. The global upper limit for the permitted sulphur content in fuel is 3.5 per cent, but in October 2016 the IMO adopted a sulphur content limit of 0.5 per cent from 2020.

Especially low limits of 0.1 per cent have been introduced in so-called SECAs (Sulphur Emission Control Areas). The map below shows the SECAs that are primarily constituted by the area along the North American coasts, parts of the Caribbean Sea, the North Sea and the Baltic Sea. It is clear from the map that all Danish waters are part of the SECAs.

In order to comply with these regulations, it is necessary to use fuel with a low sulphur content or alternative fuels such as liquefied natural gas (LNG), batteries and others. Another option is to clean the smoke containing sulphur by means of a so-called scrubber (smoke gas cleaning system) so that the sulphur is not emitted along with the exhaust gas.

In EU waters, the international regulations have been introduced by means of the Sulphur Directive, which has been transposed into Danish law through the sulphur order.

Regulation responsibility

The Ministry of the Environment is responsible for the regulation of ships' sulphur emissions, while the Danish Maritime Authority assists with the practical control of ships flying the Danish flag and of foreign ships in Danish ports. In addition, the Danish Maritime Authority takes part in international negotiations and cooperation on the implementation and enforcement of the regulations.

In general, Denmark is striving to ensure that the regulations are enforced effectively in all SECA countries. Firstly, this will contribute to limiting the harmful effects to the environment. Secondly, it is important to ensure a high degree of compliance through effective enforcement in order to maintain a level playing field. This is especially important in the sulphur area since it is costly for shipowners to meet the sulphur limits in the SECAs.

The SECA countries have drawn up a common brochure that provides a brief overview of the new regulations as well as assistance for complying with them (see below).

Together with the Danish Environmental Protection Agency, the Danish Maritime Authority has drawn up an action plan for enforcement of the sulphur regulations in which you can, inter alia, read more about the measures taken by the authorities, international cooperation and new monitoring technology (see below).

Operational questions on sulphur

Running scrubber trials? Need to file a fuel oil non-availability report (FONAR)?                                                                                           

If you are a master, shipowner, agent, technical manager, etc. and you have a sulphur related question concerned with a specific ship in Danish waters, please contact the Danish Environmental Protection Agency on  


Blue Growth and Maritime Policy

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