Increasing numbers of children around the world are suffering from respiratory problems – coughing, wheezing and asthma attacks. Although the key external causes of these diseases were identified a long time ago (traffic and industrial air pollution), it had not previously been possible to distinguish clearly between these two factors so as to have a targeted impact on them.

Researchers at the Helmholtz Centre for Environmental Research (UFZ) and the University of Leipzig carried out research in this area together with colleagues from the University of La Plata and can now confirm that air pollution caused by industry has even more grave effects than vehicle exhaust fumes.

The recently completed study on 'Combined effects of airborne pollutants as risk factors for environmental diseases' was conducted as part of a long-standing collaborative venture, supported by the international office of the German Federal Ministry of Education and Research, between the Helmholtz Centre for Environmental Research (UFZ), the University of Leipzig and the University of La Plata in Argentina. The results have been published in several  journals, including the Journal of Allergy and Clinical Immunology and Toxicology.

The UFZ researchers, who work in the Division of Health Research in Leipzig, concentrated on three courses of analysis: "Firstly," says Leipzig-based biologist Andrea Müller, "we used measurement techniques to draw accurate conclusions about the actual pollution of breathing air. We filtered out particulate matter of different grain sizes, polycyclic aromatic compounds, such as benzo(a)pyrene, that adhere to these particles, and volatile organic compounds, such as benzene and hexane. Secondly, we tested their toxic and mutagenic properties. We selected four comparative source regions: a residential area in the immediate vicinity of Argentina's largest oil refinery, an area with heavy traffic in the centre of La Plata, a suburban area and a rural area."

The children whose health formed the basis of the third course of analysis were selected from the same four areas. Around 1200 girls and boys aged between six and twelve were involved in the research that lasted about two years. With a parent-completed questionnaire data about the children's health symptoms were asked, such as coughs, wheezing, pneumonia and asthma attacks. Some of the children from each of the four regions were also invited to take a lung function test by the local paediatricians involved in the project. During the test the children were asked to blow into measuring devices – first hard and then slowly. This provided a measurement of the extent to which their bronchial tubes were constricted and therefore limited in function.

When all these measurements were concluded in La Plata at the end of 2006, thousands of pieces of data had to be compiled and correlated. It is possible to draw some notable conclusions from the columns of numbers and tables. They show, for instance, that the different respiratory disease symptoms in the industrial areas included in the study affect between a quarter and a third of all children. In the suburbs and in the countryside only half as many children tend to be affected and even in the city centre only around one or two per cent more children are affected than in the relatively unpolluted areas. The lung function of children from the industrial area was also significantly impaired. The researchers had not been expecting to find such a marked contrast.

Key culprits also appear to have been filtered out of the mass of pollutants. "Using novel statistical techniques, we identified the fingerprint of the industrial pollution in all sampled areas," says Leipzig-based meteorologist Dr. Uwe Schlink, explaining the analysis. "The level of the pollution, however, depends on the distance, season and weather situation. With an annual average of 20 micrograms of benzene per cubic metre air measured in the industrial areas of La Plata, but only 2.9 at traffic junctions in the city and 1.9 in rural areas, the health risk of industrial emissions is clear."

However, the research was about more than drawing scientific conclusions about which pollutants are the main cause of health problems. The researchers in Leipzig and their Argentinean colleagues in particular, were and still are working to raise public awareness of their research findings. They do this through parents' meetings at schools associated with the project and through lectures at the University of La Plata, through international publications and by lobbying government authorities and businesses. "At least we have helped change things for children in La Plata already," Andrea Müller is pleased to report: Because the chemical companies felt under pressure, they are now modernising their plants. "What would be interesting now would be to see how quickly the air pollution diminishes and to what extent children's health improves as a result. Whether the total mass of particulates or the number of particles per cubic centimetre is more important in terms of health problems and how we can influence climate impacts are also very topical questions," says physicist Dr Ulrich Franck. "In any case, we will continue to research these topics also in other cities around the world."

(Science Daily, 21/07/2009)