Preliminary assessments of spatial influences in the Ambos Nogales region of the US Mexican border

Ambient air measurements collected from 1994 to 1995 were used in a preliminary assessment of potential source and spatial influences in the Ambos Nogales border region ŽNogales, Arizona, USA and Nogales, Sonora, Mexico.. In this assessment, volatile organic compounds ŽVOC. and particulate matter ŽPM. species were used from four sites, two on either side of the border. An examination of median levels and principal component analysis indicated the dominance of soil dusts and mobile sources. Pairwise comparisons of sites for VOCs associated with mobile sources revealed statistically significant differences between sites in the central Nogales area vs. the two sites furthest from the border. Particulate lead at Mexican sites was higher and significantly different vs. US sites. Although further analyses are necessary, findings suggest that local and immediate mobile other anthropogenic and soil dust influences are present throughout Nogales, with particulate lead from leaded motor vehicle exhaust or soldering operations being a possible influence on the Mexican side