Ambient, indoor and personal exposure relationships of volatile organic compounds in Mexico City Metropolitan Area

Abstract

Air pollution standards and control strategies are based on ambient measurements. For many outdoor air pollutants, individuals are closer to their sources (especially traffic) and there are important indoor sources influencing the relationship between ambient and personal exposures. This paper examines the relationship between volatile organic compounds (VOCs) measured at central site monitoring stations and personal exposures in the Mexico City Metropolitan Area. Over a 1-year period, personal exposures to 34 VOCs were measured for 90 volunteers from 30 families living close to one of five central monitoring stations. Simultaneous 24-h indoor, outdoor and central site measurements were also taken. Dual packed thermal desorption tubes and C 18 DNPH-coated cartridges were used for sampling VOCs and these were analyzed by GC/MS and HPLC, respectively. A factor analysis of the personal exposure data aided in grouping compounds by the most likely source type: vehicular (BTEX, styrene and 1,3-butadiene), secondary formed or photochemical (most aldehydes), building materials and consumer products (formaldehyde and benzaldehyde), cleaning solvents (tetrachloroethene and 1,1,1-trichloroethane), volatilization from water (chloroform and trichloroethene) and deodorizers (1,4-dichlorobenzene). Mean ambient, indoor and personal concentrations were 7/7/14 mg/m 3 for benzene, 1/3/3 for 1,3-butadiene, 6/20/20 for formaldehyde and 3/9/50 for 1,4-dichlorobenzene. Geometric mean (GM) ambient concentrations of trichloroethene and carbon tetrachloride were similar to GM personal exposures. While outdoor and indoor home GM concentrations for most vehicular related compounds (benzene, MTBE, xylenes and styrene) were comparable, the GM personal exposures were twice as high. Indoor concentrations of 1,3-butadiene, 1,1,1-trichloroethane, tetrachloroethane, chloroform, formaldehyde, valeraldehyde, propionaldehyde and n-butyraldehyde were comparable to personal exposures. For certain compounds, such as chloroform, aldehydes, toluene, 1,3-butadiene and 1,4-dichlorobenzene, GM personal exposures were more than two times greater than GM ambient measurements.

Occupational Exposure to Volatile Organic Compounds and Aldehydes in the U.S. Trucking Industry

“…While a number of studies have measured exposure to VOCs and aldehydes (13,14,(23)(24)(25)(26)(27)(28)(29), none have concentrated specifically on an occupational setting with intense and prolonged exposure to diesel exhaust and exhaust from other combustion sources. However, a few studies have focused on VOC and aldehyde exposures in similar microenvironments to those observed in our study, including background, traffic, and transportation depots.…”

“…However, a few studies have focused on VOC and aldehyde exposures in similar microenvironments to those observed in our study, including background, traffic, and transportation depots. These studies include exposure data from the U.K. (14), Mexico (23), and Hong Kong (24), which are provided in Table 5 for comparison. Our driver exposures are lower than the least exposed microenvironment in the U.K. study (bus station), and exposure to formaldehyde and acetaldehyde is somewhat higher for our drivers compared with roadside observations made in Mexico and Hong Kong.…”

DNA Adducts and Lung Cancer Risk: A Prospective Study

“…For each home address, we also assessed whether the home was located in a major street (yes/no). Several studies have documented substantial differences in concentration of traffic-related pollutants between traffic and background locations (12)(13)(14). For all homes, we used detailed Internet maps to evaluate whether the home was located in a major street (yes/no).…”

Air pollution and risk of lung cancer in a prospective study in Europe

“…Several studies have documented substantial differences in concentration of traffic-related pollutants between traffic and background locations. 9,10 For all homes, we used detailed Internet maps (www.streetmap.co.uk and www.mappy.com) to evaluate whether the home was located in a major street. The map-based classification of streets was validated using traffic count data obtained from Municipalities and local environmental agencies, or were downloaded from Internet sites.…”