More than half of the global population now resides in urban areas, and this urbanisation expansion presents both opportunities and challenges for public health. A comprehensive understanding of its associated health impacts is essential for advancing individual well-being and achieving broader societal health and equity. Urban environments are shaped by a complex array of interrelated factors, including air quality, climate, land, transportation, and housing. These elements affect human health through various direct and indirect pathways. This chapter thus seeks to systematically unpack the multifaceted associations between urban environments and public health, structured into four key parts. It provides an overview of current methodologies used in environmental health research. By offering practical insights and cases, this chapter aims to support further research, inform public health practice, and guide policy development, contributing to healthier urban populations and sustainable city development across the Asia-Pacific region.