The study points out that eight per cent of the existing cases of diabetes mellitus in Germany in 2014 are linked to nitrogen dioxide exposure in outdoor air. That means that about 437,000 people are suffering the disease. For existing cases of asthma, the percentage of cases which can be traced to NO2 pollution is even higher: around 14 per cent, or about 439,000 cases.
Although epidemiological studies do not allow to draw conclusions about causal relationships, they do deliver a great deal of consistent results about the statistical correlations between negative health effects and NO2 exposure.
The model calculations which were applied for the purposes of the study are based on cautious assumptions: firstly, only those diseases for which there is a strong correlation to nitrogen dioxide exposure were taken into consideration; secondly, no health impact was factored in for NO2 exposure of less than 10 μg/m3 due to a current lack of reliable research which unequivocally confirms an association between low concentrations and effects on health. Finally, certain constraints in methodology allowed for the NO2 exposure in urban and rural backgrounds only to be factored as representative of the overall population, thus excluding certain peak load areas and traffic hot spots.
In order to also assess the influence of peak loads, estimations of the traffic-related share of disease burden which is associated with NO2 were made in both urban and non-city settings. In this context, there is an increase of up to 50% in disease burden compared to regions in which only background concentrations were included. “This is proof that the number of medical conditions and deaths associated with nitrogen dioxide is much greater in places with high exposure”, said Ms Krautzberger.
Nitrogen dioxide pollution has been decreasing for a number of years overall, but current data for 2017 corroborates that many locations still exceed threshold levels. “One significant cause of harmful nitrous oxides in respiratory air is undoubtedly diesel cars – also on roads with lighter traffic”, said Ms Krautzberger.
The new study evaluated numerous earlier studies, starting by determining for which health risks there are reliable statistics about an association with NO2 exposure. Next, the study analyses the results of epidemiological research applicable to the German population.
Data from measurements and modelling of nitrogen dioxide concentrations were combined with data on population density. This data blending enabled drawing conclusions about the levels of NO2 pollution to which people in Germany are exposed in a year. By linking relevant statistics on public health (e.g. cause of death) and applying the World Health Organization’s (WHO) concept to assess the Environmental Burden of Disease, the study made calculations of the statistical incidences of disease and deaths in Germany linked to nitrogen dioxide. The study was carried out on behalf of UBA by the Helmholtz Zentrum München and IVU Umwelt.