Review of Urban Air Pollution and Health

Urban air pollution remains a critical global public health challenge, driven largely by accelerated urbanization, industrial expansion, and increasing energy demands. This narrative review synthesizes existing evidence on the characteristics, sources, and health impacts of urban air pollutants, emphasizing particulate matter, nitrogen oxides, sulfur dioxide, ozone, ultrafine particles, and emerging contaminants such as microplastics. Drawing on historical perspectives, the review highlights the evolution of scientific understanding from early smog events to contemporary concerns involving complex pollutant mixtures and systemic health impacts. The review also explores measurement and monitoring strategies ranging from fixed-site stations to mobile sensors and integrated modeling, which shape exposure assessment and epidemiological research. Evidence consistently links urban air pollution to cardiovascular, respiratory, neurological, immunological, and perinatal health outcomes, with children, older adults, socioeconomically disadvantaged groups, and those with underlying disease identified as particularly vulnerable. Mechanistic pathways, including inflammation, oxidative stress, endothelial dysfunction, and neuroinflammation, provide biologically plausible explanations for observed risks. The review further assesses public health interventions, including urban planning, transportation policies, emission reduction strategies, and risk communication frameworks. Despite advancements in regulatory standards, clean technologies, and surveillance systems, substantial inequities persist across urban populations, particularly in low- and middle-income countries. Strengthening interdisciplinary approaches, improving exposure assessment, and addressing emerging contaminants are essential to reducing the global urban air pollution burden. Keywords: Urban Air Pollution, Particulate Matter (PM), Health Outcomes, Oxidative Stress and Inflammation, and Environmental Public Health Policy.