Urban areas are increasingly subjected to high levels of environmental pollution, including particulate matter (PM), nitrogen oxides (NOₓ), ozone (O₃), and polycyclic aromatic hydrocarbons (PAHs). These pollutants pose significant risks to human health by inducing epigenetic modifications such as DNA methylation. DNA methylation, a crucial epigenetic mechanism, regulates gene expression without altering the underlying DNA sequence. Changes in DNA methylation due to pollutant exposure may contribute to the development of various diseases, including respiratory disorders, cardiovascular diseases, and cancer. This review synthesizes recent research on how exposure to environmental pollutants affects DNA methylation in urban populations, discussing mechanisms, health implications, and future research directions.