Prof. dr. Pieternel F. Levelt Abstract for NVR, August 2020 In the 19th and 20th century the chemical composition of the atmosphere did change drastically as a result of human activities. Therefore the Dutch Nobel Prize winner Paul Crutzen called this time period the ‘anthropogenic’ epoch. The rapid worldwide growth of megacities, and its associated strong increase in air pollution, are clear examples of this. These are developments that will continue to be important in the coming decades, due to the recent climate agreement in Paris (2015), in which the reduction of greenhouse gas emissions has been put on the agenda. The recent improvement of the air quality around the world due to the COVID-19 measures suddenly reveals how a world with less emissions will look like. Nowadays we can measure the chemical composition of the atmosphere with satellites. With innovative satellite instruments of Dutch origin,  such as OMI and TROPOMI,  daily global maps of air pollution and greenhouse gases are measured on urban scale resolution. During the lecture, an outline will be given of the major research questions in the atmospheric climate domain, and their importance for air quality and climate policy. Further, the satellite measurement technique will be explained, and what these measurements can bring for as well research as climate policy, now and in the future. Examples of COVID-19 reduction of air pollution, methane emission from the oil and gas industry, as well as the potential of satellite measurements for the nitrogen deposition policy , will be shown.