Indicator 3.2.b Share of the population with excessive exposure to PM₁₀

Text from the Indicator Report 2022 

Direct sources of particulate matter are the industrial generation of energy and heat, agriculture, road traffic and heating, particularly with solid fuels and more especially with wood in household fireplaces or stoves. Particulate matter, however, can also occur through the formation of secondary particles as a result of chemical reactions with precursors such as sulphur oxide, nitrogen oxides, ammonia and organic carbon.

The particulate matter (PM₁₀) contained in the air is measured at a total of more than 370 air monitoring sites in both metropolitan and rural areas of Germany. For methodological reasons, the indicator is based only on the readings from the monitoring sites that are not exposed to direct particulate emissions from traffic or to any other significant local sources, because these measure only high localised concentrations (hot spots) and not area-wide particulate air pollution. From a combination of model results with the measured monitoring data on background concentrations, the particulate concentrations for the whole area of Germany are obtained. These concentrations are combined with information on population distribution to determine the number of persons who are exposed to annual mean particulate pollution of more than 20 micrograms per cubic metre of air at their place of residence. Rather than indicating nationwide compliance with the guideline value, the indicator merely shows that the value is not exceeded at the population’s places of residence. Neither does it give any indication of the exposure level of the population in total nor its variation in the course of the year. Since the modelled calculation is based only on measuring stations that are not exposed to direct particular matter emissions from local sources, it may well be assumed that the indicator underestimates the level of pollution. In addition, this indicator makes no provision for the separate analysis of pollution caused by finer particulate matter particles (PM₂.₅ and PM₀,₁).

The last few years from 2007 to 2020 have seen a significant reduction in particulate matter pollution caused by PM₁₀. While in 2007 the average pollution exposure of the population was still 18.9 µg per m³ of air, in 2020 it was just 12.3 µg per m³. During the same period, the number of people exposed to an annual average of more than 20 µg PM₁₀ per m³ of air at their place of residence has also fallen considerably – from around 29.7 million people in 2007 to only around 400,000 people in 2020.

Weather also influences the measurements of airborne particulate matter. Part of the reason for the sharp drop in 2011 and subsequent years is presumably that there were relatively few instances of temperature inversion in the winter months, although that curve has flattened out since 2015. Depending on wind speed, direction and air temperature, particulate matter may be transported into other regions and countries or else, during inversions, may become more concentrated at its place of origin.

If the average development of the past few years continues, it is likely that the achieved target of exposing the population nationwide to a background particulate matter pollution of less than 20 micrograms per cubic meter of air on an annual average can be sustained.

The synoptic table provides information about the evaluation of the indicator in previous years. It shows if the weather symbol assigned to an indicator was rather stable or volatile in the past years. (Evaluation of the Indicator Report 2022 )

Indicator	3.2.b Share of the population with excessive exposure to PM₁₀
Target	WHO particulate matter guideline value of 20 micrograms/cubic metre for PM₁₀ to be adhered to as widely as possible by 2030
Year	2017	2018	2019	2020
Evaluation