At a glance
- The exposure of the population to particulate matter (excluding traffic-related measuring points) was significantly lower in 2018 than in 2010.
- Particulate matter concentrations in ambient air are considerably affected by weather conditions which may vary substantially within the year and from one year to another.
- The German Environment Agency (UBA ) proposes a target of keeping the exposure of the entire population below the World Health Organisation's (WHO) guideline value for particulate matter (PM2.5) of 10 µg/m³ as an annual average by 2030.
Particulate matter in ambient air is harmful to human health. The particles enter the human body through the respiratory system. Depending on the size of the particles, they can penetrate deeply into the respiratory system. Particularly small particles (aerodynamic diameter less than 1 µm) can enter the blood stream when penetrating the pulmonary tissue. There is clear evidence that particulate matter can trigger various diseases (see 'Particulate matter').
Particulate matter is mainly the result of human activities (e.g. combustion processes), but is also released by mechanical processes (e.g. the abrasion of tires and brakes, the handling of bulk goods). Part of the particulate matter is produced by chemical reactions of other air pollutants and is therefore referred to as "secondary" particulate matter. It is produced in the atmosphere from precursor substances such as nitrogen oxides and ammonia.
The indicator focuses on the particulate matter exposure levels from rural and urban background areas, but does not take into account severely polluted areas such as roads with high traffic volumes or areas that are close to large industrial plants. It can therefore be assumed that the approach used here underestimates the exposure level. The guideline value of the WHO for health protection is used as the standard of evaluation for the indicator. The UBA considers the limit set by the European Ambient Air Quality Directive (EU DIR 2008/50/EC) to be too high and insufficient for the protection of human health.
Assessing the development
At almost 54 million in 2018, the number of people in Germany exposed to concentrations of 2.5 particulate matter (PM2.5) above the WHO guideline is significantly lower than at the beginning of the time series. This is mainly due to the fact that measures to reduce emissions are proving successful, especially in the transport sector. In addition, particulate matter concentrations in ambient air are considerably affected by weather conditions which might vary substantially from one year to another.
The EU Air Quality Directive defines a mean annual a limit value of 25 µg/m³ of air for PM2.5 to protect human health. In Germany, this annual limit value has not been exceeded in recent years. However, the WHO recommends a more stringent guideline value of 10 µg/m³ (WHO 2006). The UBA proposes that by 2030 the exposure of the population should be below the WHO limit value for particulate matter (PM2.5) of 10 µg/m³ as an annual average.
Impulses for a reduction in particulate matter pollution can be expected above all from the measures of the national air pollution control programme, which was adopted by the German government in 2019. These measures (in particular the phasing out of coal and the reduction of ammonia emissions from agriculture) will significantly reduce emissions of particulate matter and its precursor gases by 2030. The national programme is based on European Directive 2016/2284.
The indicator is calculated by combining modelled data from the REM-CALGRID chemical transport model, PM10 measurement data provided by the Federal States of Germany and the UBA and additional interpolation procedures. The PM10 data are converted to PM2.5 data using a constant conversion factor of 0.7 and are then combined with population density maps to introduce a population weighting scheme. Only those measuring stations that are not directly exposed to particulate matter emissions, for example from traffic, are considered for the indicator. For more methodical details, see Kallweit et al. 2013 (in German, abstract in English).