At IMO, the Marine Environment Protection Committee (MEPC) in the mid-1980s had been reviewing the quality of fuel oils in relation to discharge requirements in Annex I and the issue of air pollution had been discussed.
In 1988, the MEPC agreed to include the issue of air pollution in its work programme following a submission from Norway on the scale of the problem. In addition, the Second International Conference on the Protection of the North Sea, held in November 1987, had issued a declaration in which the ministers of North Sea states agreed to initiate actions within appropriate bodies, such as IMO, "leading to improved quality standards of heavy fuels and to actively support this work aimed at reducing marine and atmospheric pollution."
At the next MEPC session, in March 1989, various countries submitted papers referring to fuel oil quality and atmospheric pollution, and it was agreed to look at the prevention of air pollution from ships - as well as fuel oil quality - as part of the committee's long-term work programme, starting in March 1990.
In 1990, Norway submitted a number of papers to the MEPC giving an overview on air pollution from ships. The papers noted:
Sulphur emissions from ships' exhausts were estimated at 4.5 to 6.5 million tons per year - about 4 percent of total global sulphur emissions. Emissions over open seas are spread out and effects moderate, but on certain routes the emissions create environmental problems, including English Channel, South China Sea, Strait of Malacca.
Nitrogen oxide emissions from ships were put at around 5 million tons per year - about 7 percent of total global emissions. Nitrogen oxide emissions cause or add to regional problems including acid rain and health problems in local areas such as harbours.
Emissions of CFCs from the world shipping fleet was estimated at 3,000-6,000 tons - approximately 1 to 3 percent of yearly global emissions. Halon emissions from shipping were put at 300 to 400 tons, or around 10 percent of world total.