Abstract
Levels of BTEX (benzene, toluene, ethylbenzene, and p-xylene) were determined in ambient air of an urban site located at the center of Mexico (Leon City in Guanajuato State) during two climatic seasons of 2018 (summer and autumn). Ethylbenzene (11.86 µg m−3) and toluene (11.85 µg m−3) showed the highest median concentrations during the study period. BTEX concentrations did not show a diurnal pattern but a seasonal trend was observed for benzene and toluene at a significant level of α = 0.05. Bi-variate and multivariate analysis showed significant positive correlations (at α = 0.05) among BTEX (excepting benzene), indicating common sources for toluene, ethylbenzene, and p-xylene and a different origin for benzene. A meteorological study was also conducted in order to determine the origin of air masses that could influence the BTEX concentrations in the study site. Finally, it was found that all BTEX species presented hazard quotient values (HQs) <1, indicating that there is no risk of non-cancer during the studied period. Lifetime cancer risk due to benzene exposure for the adult and child populations studied were estimated to be 7 in 1,000,000 and 1 in 100,000, respectively.
Highlights
Air quality in urban areas can be degraded by the presence of different types of air pollutants that, depending on their concentrations and toxic potential, may affect the health of the population [1].Sources of these air pollutants include the use of solvents, vehicular traffic, biomass burning, oil and gas combustion processes, forest fires, and industrial emissions, among others [2]
The results found for benzene in Leon are comparable to those found in cities such as
Concentrationsbut but statistically differences were found between summer and autumn
Summary
Air quality in urban areas can be degraded by the presence of different types of air pollutants that, depending on their concentrations and toxic potential, may affect the health of the population [1].Sources of these air pollutants include the use of solvents, vehicular traffic, biomass burning, oil and gas combustion processes, forest fires, and industrial emissions, among others [2]. Gaseous pollutants include sulfur dioxide (SO2 ), carbon monoxide (CO), nitrogen dioxide (NO2 ), organic compounds (VOCs), and ozone (O3 ), among others These compounds (excepting VOCs) are considered criteria air pollutants and are regulated through national standards that establish their maximum permissible levels in ambient air in order to protect human health. BTEX play a very important role in atmospheric chemistry They are considered precursors in the formation of other highly oxidizing substances in addition to ozone, such as peroxyacetyl nitrate (PAN), as well as contributing to the formation of secondary organic aerosols (SOA) [6,7].
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