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Air pollutants and global effects

While most pollution can be said to be of "local" - or national - origin, requiring local solutions, air pollution can also be a transboundary problem requiring agreement by governments world-wide or regionally on measures to deal with it. Three issues, all of which have implications for the health and well-being of people in every country, have resulted in such cooperation. These are described briefly below and in more detail in WHO pamphlet

top of page Climate Change

Also described as global warming or the greenhouse effect, most scientists now agree that the climate is warming up - the expert Inter-Governmental Panel on Climate Change (IPCC) has predicted a possible rise in the average global temperature of 1 degree Celsius by 2025 and 3 degrees Celsius before the end of the 21st century.

As well as nitrogen and oxygen, the atmosphere also contains small amounts of water vapour, carbon dioxide, methane, nitrous oxide and ozone; these are sometimes referred to as "greenhouse gases" as they keep the earth's surface about 30 degrees C warmer than it would otherwise be.

In the last few hundred years the rising human population and industrialisation have increased the levels of these gases in the atmosphere. Water vapour is an important greenhouse gas, but its concentration is determined by the weather so is beyond our control. Carbon dioxide is increasing due to the burning of coal, gas and oil (fossil fuels) and the destruction of forests. Methane (CH4) is generated through modern agricultural practices ranging from rice growing to livestock farming, as well as emissions from coal mining, natural gas production and distribution, refuse and sewage disposal.

There are still uncertainties about the effects on the climate of increasing concentrations of greenhouse gases and indeed the extent and rate at which the climate is changing.

Despite these uncertainties governments worldwide have agreed that precautions need to be taken now. Table 8 shows both the huge differences in the amount of CO2 emitted in different countries of the European Union as well as the different trends regarding CO2 emissions. Climate change is likely to affect human health through the shifts in the distribution of diseases, such as malaria and respiratory disorders (IPPC, 1995).

Local authorities can also help to reduce emissions of greenhouse gases by, for example:

  • reducing fossil fuel emissions of carbon dioxide through energy conservation and energy efficiency programmes;
  • stopping the destruction of forests; planting trees to reabsorb carbon dioxide from the atmosphere;
  • encouraging the use of timber from sustainable managed sources for building, rather than energy intensive materials such as steel, bricks and cement;
  • encouraging the reduction in use, and where possible elimination, of products containing CFCs - (see B2 below);
  • reducing transport emissions.
CO2 emissions in the EU
Country Millions tons
in 1990
Millions tons
in 1993
Variation Tons per inh
in 1993
Belgium 110.7 109.1 - 1.4 10.8
Denmark 52.2 57.8 + 10.7 11.1
Germany 993.3 916.1 - 7.7 11.3
Greece 73.3 72.7 - 0.8 7.0
Spain 209.4 223.5 + 6.7 5.7
France 367.4 356.0 - 3.1 6.2
Ireland 30.6 29.9 - 2.3 8.4
Italy 401.6 390.6 - 2.7 6.8
Luxembourg 12.2 12.7 + 4.1 31.9
Netherland 156.7 160.3 + 2.3 10.5
Portugal 39.8 44.4 + 11.6 4.5
United Kingdom 578.8 556.2 - 3.9 9.6
Source: EEA
top of pageDepletion of the Ozone Layer

Current Controls under the Montreal Protocol and subsequent amendments

  • Chlorofluorocarbons: based on 1986 consumption levels, 75% reduction by 1 January 1994; phase out by 1 January 1996. Less developed countries phase out by 2010.
  • Halons: based on 1986 levels, phase out by 1 January 1994; less developed countries phase out by 2010.
  • Carbon Tetrachloride: Based on 1989 levels, 85% reduction by 1 January 1994; phase out by 1 January 1996.
  • 1,1,1-trichloroethane: based on 1989 levels, 50% reduction by 1 January 1994; phase out by 1 January 1996.
  • Methyl Bromide: for developed countries, freeze on production and consumption at 1991 levels from 1 January 1995; 25% reduction by 2001, followed by 50% reduction by 2005 and phase out by 2010, subject to exemption for critical agricultural uses. Less developed countries are to freeze production and consumption of methyl bromide in 2002, with the scope for further controls being discussed in 1997.
  • Hydrochlorofluorocarbons: developed countries, freeze at 2.8% of CFC and HCFC consumption in 1989 from 1 January 1996 levels; 35% reduction by 2004; 65% by 2007; 90% by 2010; 99.5% by 2013; phase out by 2020, subject to limited exemptions for existing equipment. Less developed countries are to freeze their consumption of HCFCs in 2016 and phase them out entirely by 2040.
  • Hydrobromofluorocarbons: phase out from 1 January 1996.

Concern over depletion of the stratospheric ozone layer - which helps to filter out some of the sun's harmful rays - was first raised in the 1970s. Exposure to these rays (ultraviolet radiation) increases the risk of skin cancer and eye cataracts, can depress the human immune system, and harm aquatic systems and crops. Scientists now reckon that over the last ten years or so average global ozone concentrations have decreased by 3%.

Current efforts to reduce production and use of chemicals affecting the ozone layer will however not have an immediate effect in restoring the ozone layer; in fact damage is expected to go on getting worse until 2000; it should then begin to improve so long as individual countries adhere to the timetables in the Montreal Protocol and EU Regulations.

Many manufacturers now use alternatives to CFCs and wherever possible local authorities should consider using products that do not contain ozone depleting chemicals. Consumers should also be encouraged to switch to CFC-free products. As refrigerators which do not contain CFCs become available, local authorities should encourage consumers to dispose of their old unit safely, perhaps by having it removed by the manufacturer or retailer as CFCs can be recycled.

top of page Acid Rain

The term "acid rain" was used as long ago as 1858 to mean rain made more acidic by acid gas pollution. A more accurate term is acid deposition. Wet deposition occurs when pollutants are carried in rain, snow, mist and low cloud; pollutants may be wet-deposited after being carried long distances. Dry deposition is the direct fallout of acid pollutants and mostly occurs close to the source of emission.


Table 9: Origin of Sulphur Deposition in Selected European Countries, Average 1985-1995
Country Foreign
Belgium 64 29 7
(former) Czechoslovakia 55 40 5
France 45 35 16
Germany 34 60 6
Italy 38 46 16
Norway 69 4 27
Poland 52 43 5
Romania 54 36 10
Sweden 72 9 19
United Kingdom 14 80 6
Source : EMEP/MSC-W Report 1/96

In the late 1960s and early 1970s, Scandinavian rivers and lakes and their aquatic life began to show signs of being adversely affected by pollution, and in the late 1970s trees in Central European forests showed signs of being similarly affected. Investigations suggested the causes to be acidification of the ground and the water from atmospheric depositions of sulphur dioxide and nitrogen oxides - from mainly industrial sources - carried in the air over long distances.

The Convention on the Long Range Transport of Air Pollution was adopted in 1979. The Convention covers Europe and North America and calls on countries to "endeavour to limit and, as far as possible, gradually reduce and prevent air pollution, including long range transboundary air pollution". The protocols under the Convention aim to reduce emissions of pollutants which can result in acid deposition and ground level ozone formation.

Since most acid pollution comes from burning fossil fuels, local authorities can help to reduce national emissions by reducing the overall demand for energy, by encouraging energy conservation and by improving the efficiency of electricity generation.


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