Not all particulate matter is the same: this is one of the denominators that can be traced back to two studies published by Swiss researchers in November. Marianne Geiser, professor emeritus at the Institute of Anatomy at the Medical Faculty of the University of Bern, has used realistic lung cell cultures to demonstrate that it is the origin of the fine dust that determines how strong the consequences for the organism are. Geiser: “For the first time, we have succeeded in demonstrating in detail how the natural defense system of the respiratory tract reacts when it comes into contact with certain fine dusts – and how the consequences are intensified when the lungs are weakened by an illness, such as asthma or Cystic fibrosis. “
The effect on health stands and falls with the origin and thus the specific composition of the fine dust, not automatically with the amount or size of the fine dust particles. The greatest impairment is caused by metallic components (from the abrasion of brakes and tires) and by particles from the combustion of wood. Only the particles were examined – gaseous pollutants (e.g. nitrogen compounds) were not considered.
The decisive factor for fine dust is not the amount but the oxidative potential, i.e. the aggressiveness of the fine dust. “Although it is undoubtedly better if the amount of fine dust is reduced,” says Geiser, “this does not mean that the health consequences decrease to the same extent.” Fine dust of 2.5 micrometers (2.5 / 1000 one Millimeters, editor's note) makes up about two thirds of the total fine dust. “There are a lot of individual particles, so that their total surface is large.” The larger the surface, the more contact area with the lung tissue, the more likely the oxidative potential becomes a problem.
The Bern study shows that the aggressiveness of fine dust from cars and wood combustion is much higher than fine dust from other sources. This is known so well because scientists at the Paul Scherrer Institute (PSI) in Villigen, Switzerland, have analyzed the origin of the fine dust samples. PSI researcher Kaspar Dällenbach: “We still cannot conclusively say which individual substances trigger which chemical reactions and what effects this has on health. But we can now say from which sources the mix that is problematic comes from. “
In view of the findings of the Swiss researchers, even a complete conversion of private transport would not be a solution to the fine dust problem in cities, because the burden of brake and tire wear would persist. For the sake of completeness, it should be added that there are projects to better encapsulate brakes so that less fine dust escapes. And the elimination of exhaust gases from the exhaust is to be welcomed in any case, even if batteries in particular raise many environmental issues “which can have direct and indirect health consequences,” says Hans-Peter Hutter, environmental medicine specialist in the Department of Environmental Hygiene and Environmental Medicine at the Center for Public Health Med-Uni Vienna.
“In any case, the Swiss studies underline what numerous experimental work with test subjects and especially epidemiological data have indicated.” Hutter would like environmental policy to show the same determination that has been there since spring in view of the measures taken against the corona crisis. Not least because there are now the first signs of a plausible connection between fine dust pollution and the severity of corona diseases.
“First signs” because the causality has not yet been proven. The findings are based on the evaluation of statistical data that are available on fine dust pollution and severe illnesses and deaths from Corona. Though only statistical
Calculations, the results are entirely plausible. Hutter: “The inflammatory reactions in the respiratory tract and the oxidative stress caused by particles but also by nitrogen dioxide weaken the epithelial cell barrier and also the immune defense against pathogens – this increases the susceptibility to infection.”
In any case, the data from 3089 counties were analyzed – there are almost 3150 administrative units in the US states. The statistical recording ended on June 18 – on this day 116,747 corona deaths were registered in the USA (there are now more than 260,000). At that time, no corona deaths were reported in 1244 counties. For the pollutant data from the remaining 1845 counties, a mean value of the pollution of fine dust particles of 2.5 micrograms was used. The result of this calculation by the Department of Biostatistics of the Harvard THChan School of Public Health in Boston: If the fine dust pollution increases by 1 μg / m3, then there was a statistical 11% higher number of corona deaths.