Emission of particulates, EU 15

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Breathing in fine particles, particularly those under 10�m in diameter (PM10s), can increase the frequency and severity of lung problems and even trigger premature death. Despite these risks there are currently no limits set for either the direct emission of PM10.

Apart from being directly emitted into the atmosphere, PM10s are also created from precursors such as nitrogen oxides, sulphur dioxide and ammonia. The 29% drop observed to date therefore stems from reductions in both direct emissions and in emissions of these precursors. This figure, however, is rather uncertain � reliable data on organic precursors, for example, is not available, while our understanding of how the different precursors interact in the atmosphere is limited.

What is clear is that the reduction is mainly due to two factors:

• energy producers switching from coal-fired to natural gas-fired power plants and introducing abatement technologies (see Energy);
• the increasing penetration of catalytic converters in road vehicles.

Particulate emissions are therefore expected to continue falling as vehicle technologies improve and the energy sector becomes less polluting. Unfortunately, other sources � such as wood burning and emissions of organic compounds � may be more difficult to both calculate and control, with recent calculations suggesting that the above reductions in emissions will not be enough to bring PM10 concentrations below the limit value even by 2010.