Current situation of polycyclic aromatic hydrocarbons (PAH) in PM2.5 in a receptor site in Mexico City and estimation of carcinogenic PAH by combining non-real-time and real-time measurement techniques

O Amador-Muñoz; Y M Martínez-Domínguez; S Gómez-Arroyo; O Peralta

doi:10.1016/j.scitotenv.2019.134526

Current situation of polycyclic aromatic hydrocarbons (PAH) in PM_2.5 in a receptor site in Mexico City and estimation of carcinogenic PAH by combining non-real-time and real-time measurement techniques

Sci Total Environ. 2020 Feb 10:703:134526. doi: 10.1016/j.scitotenv.2019.134526. Epub 2019 Nov 2.

Authors

O Amador-Muñoz¹, Y M Martínez-Domínguez², S Gómez-Arroyo², O Peralta²

Affiliations

¹ Centro de Ciencias de la Atmósfera, Universidad Nacional Autónoma de México. Circuito exterior 04510, Ciudad Universitaria, Ciudad de México, Mexico. Electronic address: oam@atmosfera.unam.mx.
² Centro de Ciencias de la Atmósfera, Universidad Nacional Autónoma de México. Circuito exterior 04510, Ciudad Universitaria, Ciudad de México, Mexico.

PMID: 31767312
DOI: 10.1016/j.scitotenv.2019.134526

Abstract

Air pollution is a public health concern. Polycyclic aromatic hydrocarbons (PAH) are ubiquitous atmospheric pollutants contained in the atmospheric aerosol. PAH in particulate matter with diameters ≤2.5 µm (PM_2.5) represent a human health risk due to their toxic properties. In this study, PAH in PM_2.5 at a receptor site of Mexico City during the dry cold season were determined. The most abundant PAH (median, 10-90th percentile, pg m^-3) were benzo[ghi]perylene (467, 291-697), followed by pyrene (427, 218-642). A decrease around 40% in the carcinogenic PAH onto PM_2.5 was calculated with respect to the same PAH measured a decade ago, at the same receptor site, despite of increase in vehicle fleet. The PAH decrease trend agrees with the decrease trend of CO, NO and NO₂, released into the air by similar emission sources than PAH. Control emissions strategies implemented by local and federal authorities are discussed. PAH analyses were carried out by non-real-time and real-time methods. The PAH non-real-time method involved PM_2.5 sampling, sample treatment and gas chromatography-mass spectrometry analysis. The PAH real-time method involved the use of a photoelectric aerosol sensor (PAS). The PAH determination by non-real time method was selective and efficient, with recoveries between 75 ± 14% and 98 ± 26%. By combining non-real-time and real-time methodologies, multivariate regression models were obtained based on PAS response, NO₂ and wind speed to estimate PAH in PM_2.5 at low-cost (r² = 0.59 to r² = 0.89). Fossil fuel combustion from vehicles was the major source around the sampling site. Diagnostic ratios (DR) based on retene, chrysene, and triphenylene, suggested biomass burning emission sources. Photo-oxidation in sunny months was observed based on benzo[a]pyrene, benzo[ghi]perylene, benz[a]anthracene, indeno[1,2,3-cd]pyrene and black carbon. The correlation analyses suggested transport of PM_2.5, O₃, BC and SO₂ to the sampling site, and local emissions of PAH, NO and CO.

Keywords: Air quality; Diagnostic ratio; Emission sources; Low-cost techniques; Public policies.