Increase of the environmental pt concentration in the metropolitan area of Mexico City associated to the use of automobile catalytic converters

Abstract

This work shows the results of de investigations concerning Pt concentration in the environment of Mexico City, product of the impact of the use of catalytic converters in the urban area. This research was carried out by assessing Pt concentration in dust samples and PM2.5 collected in the metropolitan area of Mexico City. Dust samples were divided in “road dust” and “urban dust” according to vehicle traffic exposure. Pt concentration in road dust samples, exposed to high traffic density, range from 37.7 to 231 µg kg−1 (mean 112 µg kg−1), whereas Pt concentration found in urban dust, collected in areas with low traffic density, varied between 26.4 and 86.6 µg kg−1 (mean 57 µg kg−1). PM2.5 samples were collected in five sites of the urban area during three different seasons (dry-warm, rainy, dry-cold). Results do not show significant spatial or temporal variation. Pt concentration ranges from 1 to 79 pg m−3. The comparison of Pt concentration in dust and PM2.5 samples presented here, with data reported for other urban areas, as well as with data previously reported for PM10 collected in 1991 and 2003 for the metropolitan area of Mexico City, allows to conclude a significant increase of Pt in this urban environment.