At a glance
- The exposure of the population to particulate matter (excluding traffic-related measuring points) was significantly lower in 2020 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 2005 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 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). Part of the particulate matter is produced in the atmosphere by chemical reactions of other pollutants (such as nitrogen oxides and ammonia) and is therefore referred to as "secondary" particulate matter.
The indicator focuses on the particulate matter exposure levels from rural and urban background areas, but does not take into account areas with increased particulate matter concentrations 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 overall exposure level of the German population.
Assessing the development
At almost 14,7 million in 2020, the number of people in Germany exposed to concentrations of particulate matter (PM2.5 – particles with a diameter up to 2.5 µm) above the 2005 WHO guideline is significantly lower than at the beginning of the time series in 2010 with about 77 million. This is mainly due to the fact that measures to reduce emissions are proving successful, especially in the transport sector. Furthermore, weather conditions have a direct influence on the particulate matter concentrations in ambient air.
The EU Air Quality Directive defines a mean annual limit value of 25 μg/m³ for PM2.5 in ambient air to protect human health (EU DIR 2008/50/EC). In Germany, this annual limit value has not been exceeded in recent years. However, the UBA proposes that by 2030 the exposure of the population should be below the 2005 WHO guideline value for particulate matter (PM2.5) of 10 µg/m³ as an annual average. Taking into account the new WHO guideline value for PM2.5 of 5 µg/m³ published in 2021, almost 100 % of the German population is exposed to values above the guideline value.
Impulses for a reduction in particulate matter pollution can be expected above all from the measures of the national air pollution control programme (BReg 2019). These measures (in particular the phasing out of coal combustion and the reduction of ammonia emissions from agriculture) will significantly reduce emissions of particulate matter and its precursor gases by 2030.
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 spatial 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).