Maritime traffic has been found to be a major source of air pollution. Ships sailing in Finnish territorial waters account for up to 96% of the sulphur emissions from transport, and for almost half of the nitrogen emissions in this branch. Ships' smokestacks put nearly 72,000 tonnes of nitrogen oxides and over 19,000 tonnes of sulphur dioxide into the air while sailing in Finnish waters in 2003. Under new emission standards taking effect in May next year, vessels sailing the Baltic Sea will be required to use fuels containing no more than 1.5% sulphur.
For instance, the fleet of the Finnish Finnlines shipping company uses more than half a million tonnes of fuel a year with an average sulphur content of two percent. Emission standards are also to be set for nitrogen, but the reductions are to be achieved through improvements in engine design, rather than fuel composition. Most Finnish cargo vessels use fuel that exceeds the upcoming limit. According to the Finnish Maritime Administration, most ships sailing under the Finnish flag burn fuel with a sulphur content of less than two percent. The average figure is affected by the fact that the large ferries plying passenger routes between Finland and Sweden have long used fuel with a sulphur content of less than 0.5%.
This is because Swedish environmental legislation offers the incentive of lower harbour fees and shipping route fees for ships with lower emissions. A major problem is posed by foreign cargo vessels, which use cheaper fuel with high sulphur content. There is considerable variation in the fuel used by cruise ships which stop at Finnish ports in the summer, with some using fuel with a sulphur content as low as 0.1%, while others burn oil with as much as 3.5% sulphur. Shipping lines complain that low-sulphur fuel is both expensive and not always easily available in the Baltic Sea area.