Concentrations, sources, and health risk associated with exposure to BTEX at ten sites located in an urban-industrial area in the Bajio Region, Mexico

The purpose of this study was to study the spatial and temporal variation of BTEX in the ambient air of Leon, Guanajuato, Mexico, to assess the inhalation health risk to the local population from exposure to these compounds. BTEX were monitored using passive samplers during two sampling seasons (rainy 2019 and cold dry 2020), and samples were analyzed by gas chromatography with flame ionization detection. BTEX ratios and meteorological analysis suggested that the concentrations were mainly influenced by vehicular and local sources located to the SE of the study area. The sum of average concentrations of BTEX in rainy and cold dry seasons were of 3.52 +/- 0.36 mu g m(-3) and 4.11 +/- 0.38 mu g m(-3), respectively. Mean concentrations were of 0.74, 1.59, 0.48, and 0.69 mu g m(-3), for benzene, toluene, ethylbenzene, and p-xylene, respectively. The highest levels of BTEX were found in sites with an urban land-use type of medium-intensity industrial zones with high population density. The lower BTEX concentrations found during the rainy season were probably due to higher solar radiation and temperatures that favored their photochemical degradation. Bi-variate and multivariate analysis showed that the BTEX species were strongly correlated with each other and with temperature and solar radiation, indicating that they originated from common sources. Benzene and toluene correlated strongly with CO and SO2, indicating that they could originate from vehicular exhaust emissions and high-sulfur fuel combustion sources. The health risk assessment showed that the Leon city adult population is at possible risk of developing cancer in their lifetime due to exposure to the measured benzene levels, but indicated no risk of contracting respiratory and cardiovascular diseases due to inhalation of BTEX. The results suggest the need for BTEX emissions reduction policies in the study area, as well as the establishment of a Mexican standard that regulates the maximum permissible limit of these pollutants in ambient air in order to protect the health of the population.

Automated summary

The study found that the concentrations of BTEX in the air in Leon were mainly influenced by vehicular and local sources, with lower levels during the rainy season possibly due to higher solar radiation and temperatures. Substances such as benzene and toluene were strongly correlated with temperature and solar radiation, and could originate from common sources such as vehicular exhaust emissions.