Fine dust pollution is still very high for people worldwide. The daily maximum value for particles of the size PM2.5 recommended by the World Health Organization (WHO) was recently exceeded on a global average on 70 percent of all days, as a research team reports in the journal "The Lancet Planetary Health". Only 0.001 percent of people live in places where the recommended annual maximum is not exceeded.
Fine dust particles with a diameter of less than 2.5 micrometers (thousandths of a millimeter) are referred to as PM2.5. The group led by Yuming Guo from Monash University in Melbourne (Australia) determined the particulate matter pollution based on measured values and computer models for the years 2000 to 2019. PM2.5 particles can sometimes penetrate into the alveoli and the bloodstream. Long-term fine dust pollution can lead to cardiovascular diseases and lung cancer.
240,000 dead in the EU alone
According to WHO data, around seven million people die prematurely every year as a result of air pollution. According to data from the EU Environment Agency EEA, around 240,000 people died prematurely in the EU alone in 2020 as a result of exposure to particulate matter in the air around them.
According to the Federal Environment Agency (Uba), particulate matter is produced in traffic, in power plants and district heating plants, furnaces and heating systems, and in metal and steel production. It can also be of natural origin - for example as a result of soil erosion. In metropolitan areas, road traffic is the dominant source. Another important cause is agriculture: The emissions of gaseous precursors, in particular the ammonia emissions from animal husbandry, contribute to the secondary formation of fine dust, as the Uba says.
Limits have been lowered
With regard to the current study, Roland Schrödner from the Leibniz Institute for Tropospheric Research in Leipzig speaks of a promising approach that at least provides plausible data for the regions with measuring stations. The researcher, who was not involved in the study himself, also points out that the PM2.5 particle size considered is only a compromise. Particles of the size PM1, i.e. with a diameter of one micrometer or less, which represent a subgroup of the category PM2.5, are mainly harmful to health. In the future, the size categories of particulate matter could and should be recorded more precisely. It also depends on the chemical composition.
The WHO had lowered the recommended limit values for PM2.5 fine particles in 2021 because studies had shown how badly health is affected by air pollution. For the mean annual pollution, the reference value was reduced from 10 to 5 micrograms (thousandths of a gram) per cubic meter of air. According to Uba, this value was exceeded in Germany in 2022 at almost all of the approximately 200 measuring stations.
"A wealth of evidence has supported the adverse human health effects of short-term and long-term exposure to ambient air PM2.5, even at low PM2.5 concentrations," write Guo and colleagues. The team took particulate matter readings from 5,446 stations in 65 countries as the basis for a computer model that simulates the global transport of substances through the air. Supplemented by data on weather, climate, land use and geographical conditions, the global daily PM2.5 fine dust pollution was calculated with a resolution of about ten by ten kilometers. The researchers assume that their model also provides realistic values for regions where there are no measuring stations.
decline in some regions
For the period 2000 to 2019, a global annual average of PM2.5 was 32.8 micrograms per cubic meter of air. The value was highest in East Asia (including China) at around 50, followed by South Asia at 37.2 and North Africa at 30.1. The lowest values were in Australia and New Zealand (8.5), the rest of Oceania (12.6) and South America (15.6). The daily maximum value of 15 micrograms per cubic meter of air recommended by the WHO was exceeded on more than 70 percent of all days worldwide, and on more than 90 percent of all days in East and South Asia.
According to the analysis, there was a decrease in particulate matter pollution in Europe and in some regions of North America and Africa. In Europe, the recommended daily maximum was exceeded on almost 60 percent of all days in 2000, in 2019 it was only 25 percent of all days. In Northern Europe, the values were significantly lower than in the other regions of the continent.
