Health does not just mean the absence of disease or infirmity, but a state of physical, mental and social well-being. Health outcomes are not just determined by healthcare and having access to it, but rather, are due to a mix of factors, which include living conditions and the environment. As we mark World Health Day on April 7th, this year’s theme of ‘Our Planet, Our Health’ directs our attention to the interconnectedness of human well-being to the well-being of the earth. Melisa Idris and Sharaad Kuttan speak to Dr Renzo Guinto, Chief Planetary Health Scientist at Sunway Centre for Planetary Health, to mark World Health Day.