Lewis is a doctor at Royal Perth Hospital who has an interest in environmental health and, specifically, how climate change can influence child health. He has been working at the University of Western Australia and the Future Child Health research team at the Telethon Kids Institute since 2021. He believes an understanding of the determinants of health should inform clinical practice and policy to improve the long-term health of all people. His latest work is on the quantification of child health outcomes due to climate change. This work has foregrounded the need for more population-specific geospatial studies across Australia, which the Future Child Health team are currently working on.