ENVIRONMENTAL SECURITY IN URBAN AREAS: HEALTH-RELEVANT VOC EXPOSURE IN THE GREATER CAIRO AREA, EGYPT

摘要

Air pollution of volatile organic compounds (VOCs) is a potential mediator of adverse health effects. VOCs are emitted mainly from industrial complexes, such as port facilities and refineries, any sort of traffic, and also in closed rooms during redecoration and other behavior-linked activities, such as smoking and cooking, from building materials and furniture. Assessing and managing the health risk in terms of VOCs, the spatiotemporal variation of VOC concentrations has to be taken into account. The paper presents an analysis of the spatial and temporal variation of VOCs in Cairo, Egypt, and, secondly, an approach to the temporal variation of VOCs in closed rooms in Leipzig, Germany. During a period of one month we exposed passive samplers at measuring sites that were selected randomly and that are representative of the surrounding area.Cairo is one of the most traffic-polluted cities of the world and VOCs were observed at 10 sites. Comparing the concentrations with Leipzig, we found differences in aromatics, in particular in benzene pollution. Interestingly, though outdoor concentrations are up to six times higher in Cairo than in Leipzig, indoor concentrations are generally high and at similar levels in both cities. The latter, however, differ in composition of organic compounds. In both cities, the group of aromatic hydrocarbons constitutes the principal part with more than 56%. Their main sources are traffic emissions. The indoor VOC concentrations are in Cairo 1.5 times higher than in outdoor air. In Leipzig the indoor VOC load is 6 times as high as outdoors and follows a seasonal cycle. For both cities, the composition of indoor air in apartments contrasts with the composition of outdoor air in the content of alkanes, terpenes, and aromatics. For the greater Cairo area we found that indoor air pollution exceeds outdoor pollution, in particular for alkanes. Sites characterized by high traffic have higher benzene concentrations compared to low-traffic regions. The annual cycle for total VOC concentrations observed in Leipzig proved to be the most dominant pattern. The highest concentrations occurred during the winter months and amount to approximately three to four times the summer burden. As seasonality is very important for risk management, we fit a model to the observed concentrations and develop a procedure for seasonal adjustment, which enables estimation of the annual peak concentration utilizing an observation taken in an arbitrary month.