Urban areas, lead international

In the presence of mountains and sloping terrain the wind speeds can be lower, especially at night. Buoyancy forces tend to dominate over inertial effects so that F < 1, leading to marked diurnal variations in the wind speed and direction, over the urban area and outside it. Such areas are associated with sudden changes in the airflow, internal fronts and pooling of the air in valleys, all of which greatly influence dispersion of air pollution and products from accidental releases (Hunt, Fernando and Princevac, 2003 [297]). 

It is generally accepted that increased air pollution levels do lead to corrosion of buildings and there is substantial evidence that sulphur compounds and particularly SO2 play an important role in this process. However with respect to this study the point may be made that this corrosion process is largely caused by pollutant sources within the urban area extending no more than 20-30 km and is therefore a local effect/ rather than a regional or international effect. 

The various national and international surveys included food crop data for food crop components produced in uncontaminated soils. Soils in mban areas or areas impacted by lead smelters not only have elevated Pb content, as is to be expected, but crops grown there also show Pb concentrations well above samples produced in uncontaminated soils. Table 6.48 depicts food crops with high Pb content under these conditions. Finster et al. (2004) reported that leafy and root vegetables grown in urban gardens in Chicago, IL, had Pb levels well above 10 ppm. Swiss chard was found at 22—24 ppm... 

Eugas, M., Wilder, B., Paukovic, R., Hrsak, J., Steiner-Skreb, D., 1973. Concentration levels and particle size distribution of lead in the air of an urban and an industrial area as a basis for the calculation of population exposure. In Barth, D., Berhn, A., Engel, R., Recht, P., Smeets, J. (Eds.), The Environmental Health Aspects of Lead Proceedings of an International Symposium, October, 1972, Amsterdam, the Netherlands. Commission of the European Communities, Luxembourg, pp. 961—968. 

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