Air pollution: Trend over the past 20 years in Denmark

A new report by the National Environmental Research Institute shows that the extensive reduction in emissions to the atmosphere in Denmark and the remainder of Europe has reduced pollution by most substances by a factor 5–10 over the period 1978-97. This applies to sulphur, ammonium and heavy metals in the air as well as to wet deposition of acidifying substances (sulphur, acid (hydrogen ions) and ammonium).

Conversely, little or no fall can be seen with nitrogen oxides and ammonia, which derive from traffic and agriculture. The same applies to ozone.

The report gives the concentrations of sulphur and nitrogen compounds in both the air and precipitation, the amounts deposited, and the heavy metals content of airborne particles – in each case outside the towns in the socalled reference areas.

The composition and level of the air pollution depend on local conditions. In addition, the quality of the air in Denmark is strongly influenced by pollution from abroad. With most substances, up to 80% of that deposited on Denmark thus derives from foreign sources. Denmark is nevertheless a net exporter of air pollution, first and foremost sulphur and nitrogen oxides, although the amounts deposited on other countries are quite small (a few percent) compared with total deposition on those countries.

Further information: Niels Zeuthen Heidam, National Environmental Research Institute. Phone: +45 4630 1200. E-mail: nzh@dmu.dk
The report is available at: http://www.dmu.dk/1_viden/2_Publikationer/3_fagrapporter/abstrakter/abs_341_uk.asp


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