Cathryn Tonne, Research Professor at the Barcelona Institute for Global Health, is an environmental epidemiologist focusing on the health effects of air pollution from outdoor and household sources and their intersection with sustainable development. Her research has investigated exposure patterns and health effects of air pollution in high- as well as low- and middle-income countries and the health co-benefits of climate change mitigation. She is co-director of the Lancet Countdown for Health and Climate Change in Europe and leads the working group focused on mitigation actions and health co-benefits and is a member of the WHO Technical Advisory Group on Air Pollution and Health. She is coordinator of CATALYSE, a major Horizon Europe project focused on climate change and health.