Ambient air quality with emphasis on roadside junctions in metropolitan cities of Pakistan and its potential health effects

Underdeveloped countries are undergoing economic development at a rapid rate, which most often correlate with elevated urban air pollution in many cities. Pakistan is amongst those countries that are going through this industrialization phase and with a great increase in motorization and use of energy. According to the WHO1, two third of the deaths in year 2000 were caused by exposure to urban air pollution in developing countries of Asia. To provide estimates of the quantitative relation between exposures and occurrences of diseases, epidemiologic studies together with toxicological and clinical investigations are required. Owing to limitations of the available epidemiologic and environmental studies in Pakistan, no authentic correlation among afore said factors can be made. This review is based upon peer-reviewed literature on the adverse health effects of air pollution in Pakistan and other major cities around the World. On the basis of this review it is possible to assess the status and to determine the trends in air pollution sources, emissions, concentrations, and exposures in four metropolitan cities (Karachi, Lahore, Rawalpindi, and Peshawar) of Pakistan.Environmental pollution in these cities is analyzed in terms of Particulate Matter (PM) and derived particle mass concentrations. Detected 24 hour averaged PM10 and PM2.5 concentrations in all four cities are up to 6 times higher than the maximum PM concentrations recommended by the WHO guidelines. The low PM2.5/PM10 ratios revealed a high proportion of coarser particles, resulting in reduced visibility. The heavy metal concentrations from various studies are also presented for comparison with the standards set in the world.