Volatile Organic Compounds and Carbonyls Pollution in Mexico City and an Urban Industrialized Area of Central Mexico

A total of 130 volatile organic compounds (VOCs) and 14 carbonyls were measured at the Jasso (JAS) and Tepeji (TEP) sites during the warm-dry season of 2006 in Tula, Hidalgo, Mexico, a highly industrialized area with more than 120 industries. These data were compared with those obtained in Mexico City during 2006 and 2012 at an urban center (Merced, MER) site and a southwest residential (Pedregal, PED) site. Average VOC concentrations in Tula were dominated by alkanes (40.8-42.2% of the total VOCs), followed by alkenes (10.3-11.9%), oxygenated compounds (10.0-11.5%), aromatics (7.3-12.5%), halogenated species (7.0-9.3%), and acetylene (1.6-2.4%), denotating a highly reactive atmosphere. High concentrations of propane and nButane are associated with leakage, handling, and distribution of liquified petroleum gas (LPG). The highest concentrations were found for formaldehyde at 87.2 mu g m(-3), followed by acetaldehyde (52.1 mu g m(-3)) and acetone (49.7 mu g m(-3)), accounting for 96% of the total carbonyls in Tula. VOC emission sources associated with industrial processes (such as oil refineries, power plants, plastic manufacturing, asphalt production, and solvent usage), vehicular exhaust, evaporated gasoline, LPG, food cooking, and biogenic emissions were identified using the Positive Matrix Factorization (PMF) solution to the chemical mass balance (CMB) model. A health risk assessment for toxic species such as benzene, toluene, ethyl benzene and xylenes (BTEX), found a decreasing trend from 2006 to 2012. Lifetime cancer risks (LCR) from benzene ranged from 1.5 x 10(-5) to 6.1 x 10(-5) in 2006 and from 8.8 x 10(-6) to 2.2 x 10(-5) in 2012 for the urban MER site. This database establishes baselines for evaluating the effectiveness of emission reduction strategies.