Soot and Death

Scientists have linked two key air pollutants with increased death rates in 12 European cities. The findings, published in tomorrow's issue of the British Medical Journal, are sure to fuel a contentious debate in Europe and in the United States over proposed standards that would sharply reduce exposure to airborne pollutants.

An international team led by Klea Katsouyanni of the University of Athens analyzed daily fluctuations in levels of two pollutants--sulfur dioxide and particulates--and death rates in cities. They found that an average increase of 50 micrograms per cubic meter of either sulfur dioxide or black smoke (small particulates) on a given day was associated with a 3% average increase in deaths in the Western European cities studied--Athens, Barcelona, Cologne, London, Lyon, Milan, and Paris. Such pollutant levels, however, were linked to a smaller rise in death rates in the Eastern and central European cities of Bratislava, Kraków, Lódz, Poznan, and Wroclaw: Sulfur dioxide was linked to a 0.8% increase in deaths, and black smoke nudged it up 0.6%.

It's unclear why people in Eastern and central Europe, with higher average pollution levels, seem to be at less risk from daily increases in air pollution. "This was not an effect we expected," says Katsouyanni. One possibility, she and other experts speculate, is that elderly people are more vulnerable to the ill effects of air pollution and that because Eastern Europeans have a shorter average life expectancy, their cities have fewer people at risk.

The regional discrepancy is being addressed in further studies under the European Union's Air Pollution and Health: A European Approach project.