of the American Geophysical Union. In 2019, he was awarded the Vilhelm Bjerknes Medal of the European Geosciences Union. Research Jos Lelieveld's department focuses on photo-oxidation mechanisms, which play a central role in the self-cleaning capacity of the atmosphere. With the help of self-developed highly sensitive instrumentation to measure trace gases, including reactive radicals that occur in minute amounts in ambient air, to uncover the photochemical reaction chains. He and his group have specialized in the construction of new instrumentation for application on aircraft. Fast laser-optical, mass spectrometric and relatively fast gas chromatographic techniques, for example, are used to determine the key oxidants and breakdown products of hydrocarbons. The studies include laboratory investigations, field measurements on aircraft and ships, and the use of satellite observations. Also developing computer models to simulate the interactions of chemical and meteorological processes, and investigating the impact of atmospheric composition changes on climate and planetary health in the Anthropocene. Jos Lelieveld coordinated major field measurement campaigns on atmospheric chemistry and climate ‘hot spot’ regions like the Indian Ocean, the Mediterranean, the Amazon and the Middle East. He found that the atmosphere's natural self-cleaning mechanism is effectively stabilized through the rapid recycling of highly reactive radicals, buffering the changes caused by natural and anthropogenic emissions. To study the interplay between atmospheric composition and climate, Lelieveld introduced the dynamic coupling of atmospheric chemistry in general circulation models. He showed that the increase of methane not only directly causes climate warming, but also indirectly through chemical reactions in the troposphere and stratosphere. His research uncovered how clouds and aerosols influence the chemistry of the troposphere, and showed that cloud convection has a major impact on tropospheric ozone. Lelieveld quantified the global impact of air pollution emission sectors on human health, identifying agriculture and residential energy use as important anthropogenic sources of particulate matter, next to the use of fossil fuels. Further, he showed the co-benefits of air pollution control on improving human health, reversing anthropogenically perturbed rainfall patterns and limiting global warming. His work on the Middle East and North Africa showed that the region is a global hotspot of climate change, weather extremes and air pollution, which could ultimately compromise human habitability Lelieveld has an h-index of 108 (Google scholar, ) Selected publications External links Homepage of Jos Lelieveld at the MPI for Chemistry Profile of Jos Lelieveld, Max-Planck-Gesellschaft Videos Video: What are the Sources and Health