Many gaseous substances and particles can easily be transported through the air, and some can be blown extremely long distances. Traces of certain airborne pollutants can be found far from the sources of emissions located in other countries.
A wide range of pollutants
Airborne pollutants include acidifying compounds, greenhouse gases, ozone-depleting substances, substances that cause eutrophication, heavy metals, particles, persistent organic pollutants (POPs) and radioactive substances.
Currently the most significant impacts of pollution in the atmosphere itself include the intensification of the greenhouse effect, and the depletion of the stratospheric ozone layer. Other kinds of impurities can cause serious environmental problems at ground level, or when they are deposited in the soil or water.
Local and global impacts
Air pollution can cause problems on a local, regional or global scale. Local impacts include health problems and the material and visible effects of pollution on the local environment near emission sources. Regional impacts may concern such problems as the acidification of water and the soil, or high concentrations of ground-level ozone. Global impacts include climate change and ozone depletion.
Air quality in Finland is generally high, so the local impacts of air pollution are fairly limited. During periods when certain atmospheric conditions prevail, however – particularly atmospheric inversions in the winter and spring – concentrations of pollutants in the air in Finnish cities may compare to those observed in cities of similar size elsewhere in Europe.