3. At least a 75 per cent reduction in emissions of volatile organic compounds (VOCs); 4. At least a 75 per cent reduction in emissions of ammonia: and 5. At least a 75 per cent reduction in concentrations of tropospheric ozone, which may be achieved by meeting the objectives for NOx and VOCs, as above. The critical loads concept should not be used to determine the amounts by which concentrations and depositions of pollutants can be allowed to increase in areas currently receiving pollutants below the present critical loads.
As regards acid deposition, critical loads have been exceeded over three- quarters of Europe. In some central and northwestern parts of the continent the depositions are at least twenty times higher than the critical loads. Priority must be given to preventing pollution at source, by establishing this as a central criterion in both energy planning and economic development. Any strategy for reducing emissions of sulphur dioxide, NOx and VOC (including methane), has significant implications for energy use, and thus will also lower atmospheric concentrations of ozone, carbon monoxide, and carbon dioxide, which are some of the main pollutants contributing to global warming.
The urgency of meeting the reduction targets demands that a range of measures be adopted, including: 1. Using renewable energy sources: 2. Increasing the conservation of energy; 3. Increasing the efficiency of energy production, transmission, and use; 4. Switching to less polluting fuels; and 5. Applying best available techniques in the energy, transport, industry, and agriculture sectors. The price of fuel and electricity should more readily reflect the real cost to society of the social and environmental impacts of air pollution and the inefficient use of energy and other resources.
Some measures to reduce air pollutants from the transport sector in the advanced countries are: 1. The implementation of volume control, including for example that no new major roads should be built, investment in public transport and railway freight systems should be increased; 2. The adoption of plans and timetables to reduce significantly the total European volume of road and air traffic; 3. The adoption of standards for increasing the fuel efficiency of all new motor vehicles, including aeroplanes and ships; 4. The adoption of properly regulated emission standards for all new motor vehicles, including off-road vehicles, aeroplanes and ships; 5. The adoption of speed limits for road traffic at a maximum of 100 kph.
Many of the above measures may not be applicable to the less developed countries. Progressive environmental standards should not be regarded as trade barriers. Any harmonization that affects environmental standards should be at the most stringent current level. Financial incentives and disincentives, such as levies on petrol, diesel and kerosene, can be useful tools in reducing air pollution.
Income from environmental levies should be used to finance measures for pollution prevention, including investments in public transport, as well as to restore damage caused by pollution. It is important that developing countries avoid duplicating the western countries’ wasteful pattern as regards energy use, transport and consumerism. The transition in economic and political systems in central and East Europe now offers a historic opportunity for innovation towards sustainable energy and transport systems. Priority should be given to projects which discourage energy wastage and instead focus on improving energy efficiency within the energy and industrial sectors.
Renewable energy sources have a particularly important role to play, bearing in mind their advantages over nuclear and fossil-fuel-based technologies. Because of air pollution, about 14,000 lakes are now distinctly acidified in Sweden. Rapid further deterioration will ensue if acid deposition continues at the same rate as today—it being estimated that after only a few decades the number of acidified lakes will have risen to 34,000. In total, the country has something like 85,000 lakes with a surface area of more than one hectare. Acidification has extensive biological effects in lakes.
For one thing the diversity and number of aquatic species diminishes, resulting in a greatly changed ecosystem. Such effects occur already when the pH-level of the water drops below 6. Among the sensitive animal species are snails, mussels, crustaceans, and certain species of insects and fish.
As regards the effects on forest soils, the pH value of the soil on some 6,50,000 hectares of forest land in South Sweden is now under 4.4, which is thought to be a critical level at which release of potentially toxic metals to the soil water will start. In some parts, the pH values range between 4.4. and 4.
7, and unless there is a dramatic reduction of the acid deposition, the acidification of these soils too will go below critical level within a few decades. One effect of acidification is the greatly increased leaching of plant nutrients from the soil. Since 1950, in some areas more than half of the available magnesium, potassium, and calcium has been lost in this manner. Other negative effects caused by the sulphur and nitrogen pollution are changes in the flora and fauna, acidification of groundwater, reduced crop yields, damage to materials and cultural monuments, and direct impact on human health. The cause of acidification is man-made emissions to the atmosphere, primarily of sulphur dioxide and nitrogenic compounds.
The amount of acid deposition that various types of soil will manage to neutralize in the long run—the so-called critical load—will depend primarily on the mineral weathering rate. The critical load is defined as the greatest super-addition of a certain pollutant that an ecosystem can support without suffering damage in the long term. The additions of acid substances should therefore not take place at a rate exceeding that required for enabling soil weathering to neutralize them. In Scandinavia, the critical loads for acid deposition are currently being exceeded on 80 per cent of the forest area.