Ozone responses to reduced precursor emissions: A modeling analysis on how attainable goals can improve air quality in the Mexico City Metropolitan Area.

High tropospheric ozone (O3) concentrations prevent the improvement of the air quality in the Mexico City Metropolitan Area (MCMA). Although the problem has improved considerably since the 1990s, a rebound in O3 levels in recent years has raised concerns about the deteriorating air quality. The nonlinear relationship between O3 formation and the emissions of its main precursors, i.e., volatile organic compounds (VOCs) and nitrogen oxides (NOx), is a challenge when measures are enacted for effective mitigation of the O3 problem. This study evaluated the reduction in precursors, VOCs and NOx, using an up-to-date regional air quality model (HERMES-Mex-WRF-CMAQ). For evaluating realizable scenarios, the decline in VOC achieved in Japan after policy implementation was the targeted VOC reduction (40 % from area sources), and the NOx reduction observed in the MCMA during the COVID-19 pandemic was the targeted NOx reduction (40 % from mobile sources). The analysis evaluated the O3 responses to changes in a single precursor and a combination of both during a period of high O3 concentrations (April 2019). The results showed that 40 % reduction in VOC emissions would decrease the O3 8-h maximum concentrations by 16 %. However, 40 % reduction in NOx emissions would increase O3 by >15 %. The simultaneous reduction of both precursors did not significantly affect O3 levels. The diagnosis of ozone sensitivity using the H2O2/HNO3 ratios reinforced the simulation findings, indicating that VOC emissions limited ozone formation in most MCMA areas. As the simulated scenarios were based on factual case studies, our research offers insights into the realistic aims of MCMA policies to reduce O3 levels.

Relationship between air quality and asthma-related emergency hospital admissions in Mexico City 2017-2019.

BACKGROUND: Previous studies found exposure to air pollution leads to exacerbations of asthma in paediatric and adult patients and increases asthma-related emergency hospital admissions (AREHA). METHODS: AREHAs and levels of air pollutants (PM10, PM2.5 and NO2) were obtained from Mexico City for the period 2017-2019. A time-series approach was used to explore the relationship between air pollutants and AREHA. Relative risks of AREHA were estimated using a negative binomial regression in young children (less than 5 years) and adults (greater than 18 years). RESULTS: There was a positive association between AREHA and PM10, PM2.5 and NO2 in adults, which remained after mutual adjustment for these pollutants. The relative risk (RR) of admission in adults increased by 3% (95% CI 1% to 4%) for a 10 µg/m3 increase in PM10, 1% (0.03% to 3%) for a 5 µg/m3 increase in PM2.5 and by 1% (0.06% to 2%) for a 5 µg/m3 increase in NO2. In contrast, in young children, AREHAs were negatively associated with PM10 after adjustment for NO2 (RR 0.97 (0.95 to 0.99) for a 10 µg/m3 and with NO2 after adjustment for PM10 and PM2.5 (RR 0.98 (0.96 to 0.99) and 0.97 (0.96 to 0.99), respectively, for a 5 µg/m3 increase in NO2). AREHAs in children were not associated with PM2.5 after adjustment for NO2. CONCLUSIONS: Ambient air pollution, within the previous week, was associated with emergency hospital admissions for asthma to public hospitals in adults in Mexico City. The relationship in children was less consistent. Further work is needed to explore why differences between adults and children exist to inform appropriate interventions to benefit public health.

Sulfur and nitrogen compounds in wet atmospheric deposition on the coast of the Gulf of Mexico from 2003 to 2015.

The Gulf of Mexico region has important sources of acid rain precursors, located in all of the countries; U.S., Mexico and Cuba, and so it is very important to study the chemical composition of the wet atmospheric deposition in all coastal areas. For many years along the U.S. Gulf Coast, acidic precipitation has been measured. Measurements along the Mexican Gulf Coast were begun in 2003. The aim of this study was to evaluate pH, sulfate, nitrate and ammonium concentrations in wet atmospheric deposition, collected daily from 2003 to 2015 at La Mancha (LM), Veracruz and compare the values with the National Atmospheric Deposition Program (NADP) sampling sites located along the U.S. coast of the Gulf of Mexico. The annual Volume Weighted Mean (VWM) pH in wet deposition at La Mancha site ranged from 4.81 to 5.40, which is similar to the U.S. Gulf sites. Additionally, the annual VWM SO42- concentration was from 15 to 31 µeq/L, which is higher than the U.S. sites. Annual VWM NO3- concentrations were from of 3.5 to 15 µeq/L, which is lower than all the U.S. sites. At the Mexican site, the SO42-/NO3- ratio was 4.90 and higher than all of the U.S. sites, which were between 1.03 and 2.38. For LM, the median NH4+/NO3- ratio was 0.77, similar to the Florida sites (0.53-0.91), and below the values measured for Louisiana and Texas (1.07-1.5). The Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) was applied in order to identify the emission sources for the pollutants seen at LM. Trajectories showed an important transport to LM from the East (open water) during the rainy season. The region located East of La Mancha shows offshore petroleum operations as sources of acid rain precursors and deposition of acidifying and nitrogen containing compounds. It is important to consider the sulfur dioxide emission sources in the Mexico Gulf region, and to extend the atmospheric deposition sampling to other sites along the Mexican Gulf coast and Cuba.

Encuesta en población abierta respecto a términos relacionados con decisiones al final de la vida.

INTRODUCTION: Concepts related to end-of-life decisions, such as euthanasia, palliative care, advance directives and therapeutic obstinacy, are poorly understood by the general population, which, when facing a terminal situation, is not prepared to choose the best option. OBJECTIVE: Pilot study (n = 544) to find out what the open population understands about terms used in end-of-life situations in four cities of the Mexican Republic. METHOD: Survey via Internet with 18 questions about different terms. It was a descriptive, cross-sectional study. Statistical analysis was carried out. RESULTS: People older than 18 years who were not engaged in health-related professional activities were selected. CONCLUSIONS: Most terms related to end-of-life decisions were found not to be interesting to or understood by a part of the population. The least recognized term was therapeutic obstinacy (62.8%), and the most widely known, palliative care (91%); there was confusion between the terms euthanasia and assisted suicide (47.8%). Age and education level had more influence in the results, than other demographic variables.

INTRODUCCIÓN: Conceptos relacionados con las decisiones que se toman al final de la vida, como eutanasia, cuidados paliativos, voluntad anticipada y obstinación terapéutica son poco comprendidos por la población en general, que en el momento de enfrentar una situación terminal no está preparada para elegir la mejor opción. OBJETIVO: Estudio piloto (n = 544) para conocer lo que la población abierta entiende acerca de términos utilizados al final de la vida en cuatro ciudades de la república mexicana. MÉTODO: Encuesta vía internet de 18 preguntas sobre los distintos términos. Se trató de un estudio descriptivo, transversal, con análisis estadístico. RESULTADOS: Se eligieron personas mayores de 18 años que no trabajaran en profesiones relacionadas con la salud. CONCLUSIONES: La mayoría de los términos del final de la vida no interesaron ni fueron entendidos por parte de la población. El término menos reconocido fue la obstinación terapéutica (62.8 %) y el más conocido, cuidados paliativos (91 %); se confunden los términos eutanasia y suicidio asistido (47.8 %). La edad y escolaridad resultaron de mayor influencia en los resultados, que las otras variables demográficas.

Encuesta en población abierta respecto a términos relacionados con decisiones al final de la vida / Open population survey regarding terms related to decisions at the end of life

Resumen Introducción: Conceptos relacionados con las decisiones que se toman al final de la vida, como eutanasia, cuidados paliativos, voluntad anticipada y obstinación terapéutica son poco comprendidos por la población en general, que en el momento de enfrentar una situación terminal no está preparada para elegir la mejor opción. Objetivo: Estudio piloto (n = 544) para conocer lo que la población abierta entiende acerca de términos utilizados al final de la vida en cuatro ciudades de la república mexicana. Método: Encuesta vía internet de 18 preguntas sobre los distintos términos. Se trató de un estudio descriptivo, transversal, con análisis estadístico. Resultados: Se eligieron personas mayores de 18 años que no trabajaran en profesiones relacionadas con la salud. Conclusiones: La mayoría de los términos del final de la vida no interesaron ni fueron entendidos por parte de la población. El término menos reconocido fue la obstinación terapéutica (62.8 %) y el más conocido, cuidados paliativos (91 %); se confunden los términos eutanasia y suicidio asistido (47.8 %). La edad y escolaridad resultaron de mayor influencia en los resultados, que las otras variables demográficas.

Abstract Introduction: Concepts related to end-of-life decisions, such as euthanasia, palliative care, advance directives and therapeutic obstinacy, are poorly understood by the general population, which, when facing a terminal situation, is not prepared to choose the best option. Objective: Pilot study (n = 544) to find out what the open population understands about terms used in end-of-life situations in four cities of the Mexican Republic. Method: Survey via Internet with 18 questions about different terms. It was a descriptive, cross-sectional study. Statistical analysis was carried out. Results: People older than 18 years who were not engaged in health-related professional activities were selected. Conclusions: Most terms related to end-of-life decisions were found not to be interesting to or understood by a part of the population. The least recognized term was therapeutic obstinacy (62.8%), and the most widely known, palliative care (91%); there was confusion between the terms euthanasia and assisted suicide (47.8%). Age and education level had more influence in the results, than other demographic variables.