Specificproblems ofharbourscities In a harbour town, for example, it may make sense to address SOx and NOx emissions from maritime transport in addition to road transport, since the port itself and shipping are likely to be important contributors to air pollution in the area. Besides the use of electric power for ships anchored in port, speed reduction strategies are a very effective solution to reduce air pollution in harbour cities. Speed reduction initiatives have already been launched in Californian ports and studies by the Californian Air Resource Board (CARB) indicate that reducing speed to 12 knots 40 nm outside ports could cut PM, NOx, SOx emissions by 31%, 36% and 29% respectively. Othersources ofairpollution Although transport remains a major cause of air pollution in urban areas other sources of air pollution need to be addressed simultaneously. According to recent analyses for the revision of the National Emission Ceilings (NEC) Directive, small-scale domestic combustion (e.g. wood-fired boilers and stoves for domestic heating) is the biggest source sector for emissions of PM2.5, responsible for nearly one third of the total emissions. Currently, there is no EU legislation to tackle these sources of air pollution, which stresses the need for local action. Germany has already established emission standards for domestic combustion installations, and other Member States should follow that example.