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An international research team led by the Paul Scherrer Institute PSI, the European Organization for Core Research in Geneva, carried out particularly precise measurements for atmospheric chemistry. This showed the researchers how traffic emissions and the burning of biomass are caused by harmful particles. Their results help to clarify previous models for the spread of fine dust.
Anthropogenic organic aerosols are carbon -containing particles in the air, which are part of fine dust. They represent a significant risk to health and contribute to millions of deaths worldwide every year. Especially in major cities, incomplete incineration processes into traffic, industry and households arise from which the health -damaging, lung particles form. In an international study on CERN, the European Organization for Core Research in Geneva, researchers, led by PSI, were able to gain new findings on the creation of these organic aerosols. Their results show that such pollutants often only form after several oxidation steps. It follows that pollution with anthropogenic fine dust has a larger regional impact than previously assumed. This in turn indicates that it is not sufficient to reduce the direct emissions of factories, houses and vehicles with fine dust filters, for example. Rather, the forecast gas, from which harmful organic aerosols later form, must also be controlled.
The researchers report their results in the magazine Nature Geoscience.Meinde -made fine dust, more slowdowns arise researchers assumed that organic aerosols form through a single oxidation step. Natural precursor gas such as terpenes and isoprene - these are hydrocarbons that are expelled by plants - bind to oxygen and forms in such a direct air particle. Several oxidation levels before forming fixed particles. This finding in question is the previous assumption that pollutants formed especially near the emission sources, says Imad El Haddad, project manager of the new study. Instead, it turns out that anthropogenic aerosols go through a longer development process, which means that their effects expand regionally. A unique simulation chamber of the new study was carried out at the Cloud simulation chamber (Cosmic Leaving Outdoor Droplets-in German, for example, cosmic droplets that remain outdoors) of the Cern. Seventy researchers from Europe and North America worked together to simulate urban air pollution and to pursue the development of organic aerosols. The cloud system is the cleanest atmospheric simulation chamber in the world and can regulate parameters such as temperature and pressure extremely precisely-the temperature approximately to a tenth degree. Your stainless steel cylinder has a capacity of around twenty -six cubic meters.
High -precision sensors ensure that changes inside the cylinder can be observed closely for the second. For their experiments, the researchers filled the chamber with a gas mixture that resembles the urban smog to pursue the conversion of exhaust gases into organic aerosols, and the researchers continuously measured the simulated smog. They determined the size distribution of the forming particles using the so -called mobility analysis and determined the molecular identity of the condensing vapors in real time by mass spectrometry. They also followed exactly what proportion of the forecastery and their products condensed on the walls of the chamber. This must be taken into account in the case of calculations for the formation of pollutants. Thanks to the precise observations, we can now better understand how anthropogenic aerosols arise and grow in the air, says El Haddad.
The study showed more precise predictions that a significant part of the anthropogenic organic aerosols do not form after the first oxidation, but only after additional oxidation steps, which can last between six hours and two days. The research team estimates that this multi -stage oxidation is responsible for more than 70 percent of the total anthropogenic organic aerosol pollution. Their results improve the air pollution models by running more precise predictions of the fine dust concentrationsand enable a better understanding of the regional effects. And they underline how important it is not only to contain the direct emission of fine dust through particle filters, but also the emission of peccephery materials, which only form fixed particles later. In this way, air pollution could be combated more effectively and public health improves. Text: Jan Berndorff through the PSIDAS Paul Scherrer Institute PSI develops, builds and operates large and complex research systems and provides them with the national and international research community. Own research focuses on future technologies, energy and climate, health innovation and basics of nature. The training of young people is a central concern of the PSI. That is why about a quarter of our employees are postdoctoral, doctoral or learners. The PSI employs a total of 2300 employees, which is the largest research institute in Switzerland. The annual budget is around CHF 460 million. The PSI is part of the ETH area, which also includes ETH Zurich and ETH Lausanne as well as the research institutes Eawag, Empa and WSL.
