Automotive related exposure to particulate air pollution in developing countries cities

Poor urban air quality in developing countriesis a growing public health challenge due to rises in population, industries, urbanization and vehiclesalong with insufficient air quality management. Among the range of air pollutants exposure to particulate matter (PM) is of greatest concern due to its association with chronic obstructive pulmonary diseases. The present study reports traffic related exposure to PM by the roads in Lahore, Pakistan. The measurements of mass and number of PM were carried out by GRIMM analysers (Model 1.108 and Model 1.101) and condensation particle counter (TSI 3781). The heavy metals concentration in PM was determined by Graphite Furnace Atomic Absorption Spectrophotometer (Unicam atomic absorption, Cambridge, UK).The mean hourly average concentration of PM<inf>10</inf>, PM<inf>2.5</inf>, PM<inf>1</inf> and PM<inf>10 – 2.5</inf> at the road siteswas higher during weekdays(305 μg/m³, 84 μg/m³, 61 μg/m³ and 222 μg/m³, respectively) in comparison to the weekend (136 μg/m³, 60 μg/m³, 40 μg/m³ and 76μg/m³, respectively). At the background site the levels in the same size fractions were 206μg/m³, 63μg/m³, 31μg/m³, and 143μg/m³, respectively. Likewise, the number concentration of ultrafine particles was considerably higher at road sites (417,003 #/m³) than the background(97,300 #/m³).The concentration of heavy metals in PM decreased in the following order: Si, Al, Zn, Mn, Cu, Ni, Cd, Pb. Overall, the concentration of PM<inf>10</inf>, PM<inf>2.5</inf> and toxic metals (Mn, Cd, Ni) was substantially higher than guidelines by the WHO. Furthermore, relatively higher levels of the fine fraction (PM<inf>2.5</inf> and PM<inf>1</inf>) in the background reflect their higher residence time and resultant increased risk of exposure to the wider public beyond that of the vicinity to automotive sources. Everyday commuters, mostly on two and three wheelers as well asthe residential population in urban areas are at an enhanced risk of exposure to high levels of particulate pollution.