Influence of urbanization on air quality based on the occurrence of particle-associated polycyclic aromatic hydrocarbons in a tropical semiarid area (Fortaleza-CE, Brazil)

Abstract

This study reports the first measurements of polycyclic aromatic hydrocarbons (PAHs) in particulate matter in the metropolitan area of Fortaleza-CE, Brazil. We studied the influence of urban topography on the occurrence of PAHs and the depositional flux (FPAHs) and characterized the emission sources and health risks of PAHs. Of the 16 PAHs evaluated, only 10 PAHs with more than 4 aromatic rings were found. The total PAH concentration (ΣPAHs) ranged from 1.73 to 2.83 ng m−3 . The FPAHs value ranged from 0.008 to 0.0182 μg m−2 day−1 . These fluxes are comparable to the values obtained at sites with developing urbanization or sites that use heating; however, they are smaller than the values obtained at industrial and large metropolis sites. An examination of the influence of urban topography revealed that the building density considerably increased the particulate matter concentration; however, urban vegetation had the opposite effect. Light-duty vehicles were the most important emission source of PAHs in the metropolitan area of Fortaleza. However, industrial activities (e.g., asphalt and steel production), combustion (e.g., coal and wood), and paved roads had a modest contribution. The health risk from PAHs in Fortaleza is higher at sites with a higher traffic flow, and the level of this health risk is similar to the risk level in other developing cities.