<p>As an integral component of modern urban transportation, metro systems have significantly contributed to alleviating urban traffic congestion and reducing carbon emissions. However, concerns about air quality in its confined environment, particularly the pollution by BTEX (benzene, toluene, ethylbenzene, and xylene), are growing. This study takes the Chengdu metro system as a case to evaluate the concentrations of BTEX and their potential health impacts on the public. Sampling was conducted in metro stations, carriages, and tunnels. The study found that the BTEX pollution levels in the metro system were 7.85 ± 3.03 µg/m³ in summer and 8.44 ± 3.38 µg/m³ in autumn, with toluene and xylene being the highest concentrations. No significant differences were observed between the halls and platforms, interchanges and non-interchanges, off peak and evening peaks in carriages, or in-service and off-service in tunnels. However, seasonal variations were pronounced. Health risk assessments indicated that while non-cancer risks were negligible, cancer risks in both summer and autumn (excluding passengers) exceeded the acceptable threshold of 1 × 10⁻⁶, potentially posing health threats to long-term exposed populations, particularly metro workers. This study provides a scientific basis for air quality management within metro systems and highlights the need for regulatory bodies to pay further attention to air quality issues, promoting the formulation and implementation of relevant control measures to protect the health and safety of passengers and metro workers.</p>