Researchers from the Max Planck Institute for Chemistry (Munchen, Germany) and the German Weather Service (Offenbach, Germany), who recently completed a 25-year study measuring ship-borne ozone over the Atlantic Ocean, say that the ozone trends in the northern mid-latitudes are small.

The study showed that significantly large ozone trends occur at low latitudes and in the Southern Hemisphere, implying that the ozone problem has expanded beyond the areas traditionally affected by photochemical air pollution in Europe and the United States.

The nitrogen oxides, released from the combustion of fossil fuels and from biomass burning, act as catalysts of ozone formation. In turn, this reduces air quality and impairs human health, agricultural crops and natural ecosystems.

In the post-war industrialization in the 1960s and 1970s, ozone increased rapidly in Europe and the United States. The ozone increases were moderated after 1980 by the introduction of catalytic converters in car exhausts and the mitigation of industrial air pollution.

The results of this study confirm that in the middle latitudes of the Northern Hemisphere, ozone concentrations are quite high, although the increases since 1980 have not been very large. Unexpectedly, however, in the subtropics, tropics and the Southern Hemisphere, ozone increases since 1980 have been much larger. The scientists report that in some regions, the ozone levels have even doubled in the past two decades.

The area where the high ozone concentrations have been measured is mostly downwind of Africa, and the researchers have calculated that biomass burning and increasing energy use on this continent have contributed substantially to emissions of nitrogen oxides, thus catalyzing ozone formation.

Story image courtesy of WeatherBug user Richard Gronowski, New York, New York.

Copyright 2004 Sea Technology.