Clean air - Danish efforts
A problem of increasing dimensions
Since the beginning of the 19th century the world population has increased from about one to six billions. The energy consumption has increased even more. Together with increased agricultural production, this growth has resulted in increasing air pollution with significant impacts.
The London smog with sulphur dioxide and soot was notorious for centuries, and it was not before a catastrophic episode in 1952, when pollution was than 20 times higher and there were several thousand extra deaths, that effective legislation was carried through. A corresponding - but less dramatic - development has been seen in Copenhagen.
Across all borders
To begin with the problem was partly solved by dispersing pollution from high stacks, but of course it did not disappear. Instead most of the sulphur dioxide emitted in Denmark was carried with the wind to other countries, predominantly Sweden and Norway.
In this way the precipitation was acidified, resulting in ecological damages in large parts of Europe - e.g. deaths of fish in a number of Swedish lakes. It had now become a phenomenon with a geographical extension of several thousand kilometres and a time horizon of decades. A UN conference in Stockholm in 1972 created political attention, and in 1979 the Geneva Convention on transboundary air pollution was established and signed. As a result European sulphur emissions have - by use of cleaner fuels and flue gas purification at large combustion plants - been more than halved. The Danish emissions have even been cut down to about one tenth. Also emissions of nitrogen compounds and hydrocarbons that put pressure on the ecosystems have been reduced. In Sweden with many sensitive areas, the loaded area is now halved.
Growth in Danish population and energy consumption
During the 20th century the Danish population more than doubled, from below 2.5
million to more than five million inhabitants. This has resulted in increasing energy
consumption and more intensive agriculture and, thus, increasing pressure on the
environment.
The population is still slowly increasing, mainly due to immigration, but the energy
consumption is stabilised and will be reduced.
The great challenge of the future - both nationally and globally - is to decouple
development and environmental pressure: to establish "sustainable development".
In the cities
In step with - and partly because of - the reduction of the transboundary pollution, the air quality in the cities has in several ways been improved.
Today air pollution in many big cities is dominated by emissions from car traffic. And it is a complicated matter, because many different compounds react mutually in the atmosphere, before they start to have impacts - either in the city or at long distances.
The most serious urban problem today appears to be particles. The relations are not fully understood, but especially small particles from diesel cars are thought to be dangerous. In Copenhagen the particles may result in hundreds of extra deaths per year among sensitive persons.
Research and international collaboration
The problem with air pollution used to be simple. Everybody could see the black smoke that came out of a low chimney - and their number was so small that it did not became a serious problem when the smoke was carried with the wind to other places. Now this has changed, because air pollution is dispersed at all geographical scales and the relation between emissions of contaminants, the resulting pollution of the air, and the impact of the pollution, are very complicated.
Effective management therefore requires monitoring and research. We must know the causes of pollution and how we can solve the problems in the cheapest and most efficient way. Interplay of many technical disciplines is required.
Air pollution used to be a "here and now" problem. At the fireplace in a house in the Iron Age, the quality of the air could be worse than in a street in a modern city. But when the fire was out, the smoke disappeared and the surroundings were not affected any further. Later the problems increased in scale - both geographically and in time. Today emissions from a Danish power plant can contribute to the acidification of a Swedish lake and be part of the reason why an atoll on the other side of the globe will be submersed in some hundred years. Therefore today's struggle against air pollution is not merely a local matter. It is a question of distribution of burdens between the individual nations and our responsibility towards the coming generations.
It is necessary to follow the development to detect unfortunate tendencies and to investigate whether regulatory measures have had the expected impact. And these activities must be carried out by international cooperation. If these conditions are fulfilled it will be possible directly to reduce the impact.
When the NEC Directive on national emission ceilings in Europe was acceded in the EU in October 2001 and the Gothenburg Protocol in December 1999, binding limits for permitted levels of air pollution from the individual countries were determined for the first time.
It has been estimated that if the Gothenburg Protocol is fully implemented, the acidified areas in Europe will be reduced by 85%, the eutrophied areas by 65%, and areas suffering from ozone pressures by 50%. It is further expected that the impact on human health will be significantly reduced. However, emissions of atmospheric pollutants from international shipping are still not under control. In step with reductions of emissions from landbased sources, emissions of i.a. sulphur dioxide from the shipping trade will become increasingly important.
Problems on a global scale
In the industrialised world the problems with transboundary air pollution is recognised, and the technological possibilities for solving them are available, although there is still a long way to go. In the developing countries and in the former communist countries, the economic growth still causes serious environmental damage. However, it is probably only a question of time and use of existing modern technology before the problems will be solved.
What is more serious is that global growth has moved the problems one level up, in terms of both time and geographical extension. Now it is no longer a question of compounds that can be removed by using other fuels and raw materials or by installing filters on stacks and exhaust pipes. When coal, oil or gas are used in the energy sector, the unavoidable end product in the combustion process is the gas carbon dioxide. Together with other greenhouse gasses carbon dioxide is emitted in so large amounts and has so long lifetimes in the atmosphere that the concentration increases globally. This changes the energy balance in the atmosphere and thus poses threats of climate changes that can affect the conditions for both humans and nature on the entire globe.
New challenges
Scientific investigations and international co-operation have become even more important, now that environmental problems have been moved to a global scale with a time horizon of several hundred years. Here model calculations play a decisive role. They not only give an overview of all the data that has been collected in the real world. One can also ask questions like: "What would happen if...?" The answer is not always pleasant.
The content of the leaflet
The leaflet describes first a few basics in the abatement of air pollution. Then a few concrete problems that lead up to the Gothenburg Protocol, and EU's national ceilings for limitation of transboundary air pollution in Europe are addressed. Finally Danish efforts relating to the global problems with depletion of the ozone layer and the anthropogenic climate changes are briefly described.
Information to the reader
Emissions of air pollution are most often indicated as weight (e.g. tons per year). Concentration in the air is expressed in µg (one millionth gram) per cubic meter.