The problems of the world are not categorised into disciplines. They are far more complex, a reality that the tradition of transdisciplinary research has recognised. When faced with questions in public health and sustainability, the traditional scientific paradigm often seems inadequate, and, at least in medicine, transdisciplinary research has not yet been fully appreciated or acknowledged. This lack of recognition may be partly caused by a lack of cooperation between disciplines and between science and society. In this paper, I discuss some of the challenges that scientists and policymakers face in public health and environment within a methodological context. I present transdisciplinarity as a modern research tool that should be applied in research in health and the environment and argue that these topics can be approached beyond the inherent obstacle of incommensurability between disciplines. Thus, a small step might be taken in this immense research arena.