<p>During winter, PM_2.5 Samples were meticulously collected from two metro station platforms and their adjacent outside areas in Tianjin. The mass concentrations, along with the compositions of metal and metalloid elements, polycyclic aromatic hydrocarbons (PAHs) and water-soluble ions within PM_2.5 were precisely determined. Employing the positive matrix factorization (PMF) receptor model, a detailed source apportionment of PM_2.5 was carried out at the two subway platform sites and their corresponding outdoor locations. The results revealed that the PM_2.5 concentration on the platforms was significantly higher than that in the outdoor areas. Most metal and metalloid elements exhibited higher concentrations on the platforms compared to the outside. Notably, in the metro station equipped with half - height platform gates, the concentrations of Al, Cr, Mn, Ni, Sb, Pb, Co, Naphthalene (NAP), Acenaphthene (ANA), Phenanthrene (PHE), Fluoranthene (FLT), and Pyrene (PYR) were considerably higher than those in the station with platform screen doors. In contrast, no significant differences were observed in the concentrations of water-soluble ions between the platforms and the outdoor areas. PMF analysis indicated that subway train operation and coal combustion were the dominant sources of PM_2.5 at the Honghuli Metro station (HHL) site. At the Jinghe Road Metro station (JHR) site, biomass burning, fossil fuel combustion, and brake pad wear were identified as crucial sources. For both the outside of Honghuli Metro Station (OHHL) and the outside of Jinghe Road Metro station (OJHR) sites, secondary aerosol emerged as the primary pollutant source. Significantly, the external environment of the metro stations exerted a substantial influence on the pollutant types present on the subway platforms. This study provides valuable insights into the air quality in subway environments, which is of great significance for urban environmental management and public health protection.</p>