Influence of source contributions and seasonal variations on particle-associated polycyclic aromatic hydrocarbons and cancer risks in a rapidly urbanizing South American City (Fortaleza, Brazil).

This article focuses on assessing the influence of source contributions and seasonal variations on particle-associated polycyclic aromatic hydrocarbons (PAHs) and related cancer risks in Fortaleza, a rapidly urbanizing city in the tropical semiarid region of Brazil. The study measured PM10 and PAH concentrations during wet and dry seasons, identifying vehicular emissions as the predominant source, followed by coal and wood burning and industrial activities. PM10 levels were generally higher in the dry season, while PAH concentrations showed localized increases in areas with dense urban canyons and heavy traffic during the wet season. Cancer risk assessments indicated moderate to relatively low risks compared to other global urban-industrial regions, with smokers facing approximately 22% higher relative cancer risk than nonsmokers. The findings highlight the need for targeted emission control and urban planning policies to mitigate health risks in expanding tropical urban areas.