AMBIENT AIR LEVELS OF VOLATILE ORGANIC-COMPOUNDS IN LATIN-AMERICAN AND ASIAN CITIES

Levels of volatile organic compounds (VOCs) have been measured during short monitoring campaigns in four cities in Latin America; Caracas (V enezuela), Quite (Ecuador), Santiago (Chile), Sao Paulo (Brazil), and two cities in Asia; Bangkok (Thailand) and Manila (Philippines). The a im of the study was to identify typical levels of VOCs in these cities where monitoring of this unregulated but important group of pollutant s has rarely been conducted. Levels monitored were relatively high in comparison to typical European and US levels. Mean benzene levels rang ed from 5-18 mu g/m(3) and toluene from 15-186 mu g/m(3). VOC levels i n the Latin American cities were similar and considerably lower than t hose measured in the two Asian cities. Levels in Quite were the lowest of all the cities studied and this may reflect its high altitude whic h allows the use of fuels with a low aromatic content. The relative ab undances of the different VOCs monitored and the ratios between differ ent VOCs are largely consistent with vehicles being the predominant so urce of VOCs in these cities. The levels of VOCs measured during this study were generally higher than proposed UK standards and as such rep resent a direct health risk to the inhabitants of the cities. High lev els of VOCs will also affect the incidence and severity of photochemic al episodes with further consequences for human health and the environ ment. (C) 1998 Elsevier Science Ltd. All rights reserved.