Seasonal and Diurnal Variations of BTEX in Ambient Air from a Site Impacted by the Oil Industry in Southeast Mexico.

Atmospheric concentrations of BTEX were measured in an urban site located in the vicinity of an oil storage-distribution facility in Paraiso, Tabasco, Mexico. Samples were collected during two seasons (nortes 2018 and dry 2019). The relative abundance of BTEX mean concentrations was: toluene (5.24 µg m-3) > ethylbenzene (3.92 µg m-3) > m, p-xylene (3.89 µg m-3) > benzene (2.43 µg m-3). BTEX concentrations had a clear diurnal and seasonal pattern, showing higher levels during the dry season due to differences in wind conditions, rainfall patterns and temperature. Statistical analysis showed significant positive correlations among BTEX, indicating that these compounds had common sources. Interspecies ratios revealed that BTEX were originated from sources beyond vehicular traffic and that they were influenced by the transport of local air masses. The assessment of lifetime cancer risk showed that the population in the study area is at possible risk of developing cancer.

Short-Term Effects of Atmospheric Pollution on Daily Mortality and Their Modification by Increased Temperatures Associated with a Climatic Change Scenario in Northern Mexico.

Short-term effects of air pollution on the health of residents in the Metropolitan Area of Monterrey, Mexico were assessed from 2012-2015 using a time-series approach. Guadalupe had the highest mean concentrations for SO2, CO and O3; whereas Santa Catarina showed the highest NO2 concentrations. Escobedo and Garcia registered the highest levels for PM10. Only PM10 and O3 exceeded the maximum permissible values established in the Mexican official standards. Most of pollutants and municipalities showed a great number of associations between an increase of 10% in their current concentrations and mortality, especially for people >60 years. Different scenarios resulting from climatic change were built (increases of 5-25% in daily mean temperature), but only the increase of 25% (5 °C) showed a significant association with air pollutant concentrations and mortality. All pollutants and municipalities showed significant increases in relative risk indexes (RRI) resulting from an increase of 5 °C when people >60 years was considered. Results were comparable to those reported by other authors around the world. The RRI were low but significant, and thus are of public concern. This study demonstrated that the elderly is strongly threatened not only by atmospheric pollution but also by climatic change scenarios in warm and semiarid places.