Exposure of city-dwellers to particulate matters during commuting trips in the metropolitan area of Karachi

Abstract

The brisk and persistent surge in the population, urbanization, automobiles, and industries fused with climate change and geogenic conditions have materialized in acute ambient air pollution problems in the mega city Karachi with profound health impacts. To evaluate the extent of personal exposure and quantification of the particulate matter (PM) concentrations, we organized the mobile size-segregated PM (TSP, PM10, PM7, PM2.5, and PM1) monitoring campaign in Karachi. Seven in-vehicle tracks in Karachi's diverse industrial/commercial/residential regions were investigated. High spatial variability in PM concentrations was observed along each track. Results demonstrate that commuters in Karachi were exposed to a significantly higher level of PM than several cities in high-income countries. Mean concentrations across the seven tracks were: PM1 (8.7 ± 8.0 μg/m3), PM2.5 (51.9 ± 48.0 μg/m3), PM7 (386 ± 538 μg/m3), PM10 (527 ± 646 μg/m3), and TSP (685 ± 769 μg/m3). The carcinogenic risks of PM2.5 were found to be outside the acceptable range (10−6 - 10−4). Therefore, better insight into PM pollution exposure and its determinants in Karachi should influence the development of more appropriate exposure reduction strategies and have major public health effects.