This comprehensive field campaign was conducted at six different sampling sites during winter and summer to characterize polycyclic aromatic hydrocarbons (PAHs) in PM2.5 (particles with aerodynamic diameter ≤ 2.5 µm) in Delhi, the national capital of India and one of the most polluted megacities of the world. The experimental results at city-level showed seasonal variations with higher levels of PM2.5 during winter (356 ± 136 μg/m 3) compared to that of summer (268 ± 94 μg/m 3). Similarly, the trends in seasonal levels of total PAHs showed higher concentrations during winter (75.1 ± 50.2 ng/m 3) than that of summer (10.4 ± 8.5 ng/m 3). From spatial distribution, it was revealed that urban industrial-cum-residential site had the highest levels of PM2.5 (430 ± 104 μg/m 3), and total PAHs (124.5 ± 70.7 ng/m 3) during winter compared to other five sites. Individually, the ambient concentration of benzo[ghi]perylene (winter: 14.3 ± 7.4 ng/m 3) was observed with the highest concentration followed by indeno[1,2,3-cd ]pyrene (winter: 13.1 ± 7.3 ng/m 3) at most of the sampling sites. Total benzo[a]pyrene equivalent was used in conducting human health risk assessment for possible occurrence of cancer, and the results revealed that the chances of getting cancer during lifetime exposure to particulate PAHs for adults would be 423 per million people over the entire study area (the values of possible risks at six sampling sites) exceeded World Health Organization (WHO) permissible limits. Source apportionment modeling results showed that vehicles as a whole contributed 62% to total mass of PAHs, followed by municipal waste burning as 15%, and biomass burning as 11%. With such trends of source apportionment and health risk assessment, this study concluded that PM2.5-bound PAHs in Delhi can cause serious human health implications, if not controlled with collective initiatives from scientific, policy making and regulatory bodies.