State of air quality in twin cities of Pakistan: Islamabad and Rawalpindi

Abstract

Atmospheric pollution has emerged as a disaster in developing countries like Pakistan. The aim of this study was to observe and analyze the air quality status of the twin cities of Pakistan, Rawalpindi and Islamabad, with a combined population of 15 million. The concentration of criteria pollutants along with CO₂ was measured at five different locations within these cities. Sampling was done for 24 h at each location using a mobile air quality monitoring lab. The overall concentrations of SO₂, NO_X and O₃ were found to be within the permissible limits of the US-EPA standards and the National Environmental Quality Standards of Pakistan, with higher PM₁₀ and CO₂ concentrations at most locations. The highest concentrations of PM₁₀ were observed at Saddar, Rawalpindi (184 µg m^–3), while minimum values were observed at the Blue Area of Islamabad (121 µg m^–3). The concentration of CO₂ during the study period was found to be high in almost all locations, with Saddar, Rawalpindi, indicating the highest value (409 ppm). The concentrations of CO₂ at the Blue Area and the National University of Science and Technology of Islamabad were observed to be as high as 385.3 and 246 ppm, respectively. The behavior of pollutants with different meteorological parameters was also studied. For source identification, backward air trajectories were also generated using the HYSPLIT model.