BTEX proportions as an indicator of benzene hotspots and dispersion tends in cities where sea and land breezes dominate

Abstract

There are certain spatial configurations in cities that generate areas with reduced ventilation where, consequently, air pollution can reach hazardous levels. Although urban forms have already been flagged as a factor affecting air pollution, its role in the accumulation of volatile organic compounds has not been extensively evaluated with field measurements. In order to investigate the effect of urban morphology on air pollution levels, we measured the concentration of benzene, toluene, ethylbenzene, and xylenes (BTEX) in 44 different city sites, using Radiello® diffusive passive samplers during a 1-week campaign. This work presents a method that maps a city in zones with different levels of atmospheric dispersion by analyzing the proportions of BTEX in the ambient air. The method applied to a coastal city (characterized by uniform wind patterns) revealed the existence of two clearly differentiated zones. In one of them, the mean benzene concentration was 3.26 times higher than in the other. However, the mean concentrations of the rest of BTEX were barely the same in both areas. These findings suggest that slow degradation pollutants (i.e., benzene) accumulate in poor ventilated areas, whereas faster degradation pollutants do not show accumulation. The conclusions of this study can be particularly useful in designing personal exposure assessments, optimizing the urban morphology, and improving the location of air quality monitoring stations.