The concentration of PM2.5, heavy metals (Fe, Al, Cd, As, Cu, Ni, Pb, Cr, Zn, Mn, and V), cations (Ca2+, K+, Mg2+, and Na+), anions (Cl−, SO4 2−, NO3−,and F−), and PAHs present in the atmosphere of Tehran were measured. The filters and devices used to measure PM2.5 belong to Tehran Air Quality Control Company (TAQCC). Among the 21 air pollution monitoring stations of TAQCC, 11 stations in 3 categories (traffic, urban, and suburban) were selected for this study. Urban stations were built to investigate the effect of pollutants on the population exposed to pollution in the city. These stations are located far from the main streets and high traffic streets, near residential and commercial areas and terminals. Traffic stations investigate the pollution level in streets near densely populated areas. This type of station experiences the direct impact of crowded highways and streets. Suburban stations are located around the city and are included to examine the effect of pollutants on the population in the outskirts. Following the USA Environmental Protection Agency standard, 24-h samples were taken every six days, in the periods of 22 April to 21 May and 23 July to 22 August 2015 for the spring and summer seasons, respectively. Beta-attenuation monitors (BAMs) equipped with size-selective air intakes that collect PM on fiberglass filters (ID 460130, 30 mm × 31 mm, Met One Instruments, USA) were used in keeping with the PM2.5 measurements (Watson et al., 2012). The flow of air to the BAMs was 16.1 L·min−1. The particles accumulated on 16mm diameter spots (there are 24 spots on a tape for 1 day and the tapes automatically advance by one spot every hour). After separation of the fiberglass filters from the sampling device, they were kept in aluminum foil to prevent photo degradation and evaporation loss. The samples were stored at temperatures below 4 °C until further analyses.