Evaluación de carbonilos, PM2.5 y especies de carbono negro en ambientes intramuros y extramuros de la Ciudad de México
Authors:   , Silva Gómez Sandra Isabel 
Published: April 2022

Inhabitants of urban areas such as Mexico City are exposed to various anthropogenic pollutants. Among them, atmospheric particles and volatile organic compounds (VOC), which usually exceed the limits established by current regulations. Air pollutants are of great interest because of their important role in atmospheric chemistry, the complexity of their sources, and their adverse effects on health. PM2.5 are fine particles that serve as indicators of poor air quality, such black carbon, which also contributes to global warming. Both cause serious damage to the respiratory system, mainly in children and the elderly. Carbonyl compounds are members of the VOC family, they are precursors of tropospheric ozone and are considered dangerous compounds, some of them are already classified as carcinogens. Air pollution is studied in two environments; extramural and intramural, due to the time we spend indoors (home, office, classrooms and other workplaces), which is approximately 90%. The problem of indoor pollution is caused by various factors, including the number and variety of emission sources. In this thesis, the concentration levels PM2.5, carbon species and carbonyls were evaluated in intramural and extramural environments in Mexico City. For the evaluation, three sampling campaigns for PM2.5 and carbonyls in the air were designed and carried out considering the spring, summer and autumn seasons in intramural and extramural environments. Each campaign was carried out in three areas of Mexico City: North in a house near the facilities of the UAM-Azcapotzalco, Center in the University of the Americas on Av. Insurgentes and South in the Center for Atmospheric Sciences in Coyoacán. Outdoor sampling was carried out on the buildings’ roofs of two campuses and a residence, while the indoor sampling was carried out in office areas and residence. The experimental data was carried out through the gravimetric analysis of quartz and Teflon filters, the use of thermo-optical equipment and HPLC UV-vis chromatography. As a result of this project, it was found that the concentrations of particles were higher outside the walls than inside the walls, mainly in the spring time compared to those obtained in the summer and fall of 2019. The content of carbonaceous species in PM2.5 was around 20%nof which 10% turned out to be elemental carbon and 90% organic carbon, in which PAHs can be included among other organic species. Total carbon concentrations were higher intramural than extramural. Total carbon concentrations were higher intramural than extramural. The indoor-outdoor (I / E) ratio for PM2.5 indicated that outdoor sources predominate over indoor sources. On the other hand, the average concentrations of carbonyls in the three sites were higher inside the buildings than outside, especially in the summer season. Acetone concentrations had many variations in all samplings, reaching values close to 1000 μg m-3 in the intramural area. The carbonyls with the highest concentration values were acetaldehyde and formaldehyde. Acrolein also presented some variations in its concentration, especially in summer.Propionaldehyde and butyraldehyde presented low concentrations in all samplings. The I/E ratio was evaluated for each carbonyl, which showed values greater than 1 in most cases, which confirms an important contribution from intramural sources such as the use of cleaning products, the material of the building and of furniture and human activities that could be a source of emission of carbonyl compounds.