IMO has launched a guide to the frequently asked questions on Sulphur 2020 link here

Image IMO FAQs heading

IMO has been working to reduce harmful impacts of shipping on the environment since the 1960s. Annex VI to the International Convention for the Prevention of Pollution from Ships
(MARPOL Convention) was adopted in 1997, to address air pollution from shipping.

The regulations for the Prevention of Air Pollution from Ships (Annex VI) seek to control airborne emissions from ships (sulphur oxides (SOx), nitrogen oxides (NOx), ozone depleting
substances (ODS), volatile organic compounds (VOC) and shipboard incineration) and their contribution to local and global air pollution, human health issues and environmental problems.
Annex VI entered into force on 19 May 2005 and a revised Annex VI with significantly strengthened requirements was adopted in October 2008. These regulations entered into force
on 1 July 2010.

The regulations to reduce sulphur oxide emissions introduced a global limit for sulphur content of ships’ fuel oil, with tighter restrictions in designated emission control areas.