Altitude-dependent gaseous emissions from freight trucks along the China-Pakistan Economic Corridor in Pakistan

Recent increases in emissions from freight transport have caused strong concerns about air quality in Pakistan, following the rapid development of projects related to the China-Pakistan Economic Corridor (CPEC). This study reported the first measurements of on-road truck emissions in Pakistan and inves-tigated their dependence on altitude along CPEC routes. Emissions from 70 trucks were measured on CPEC highways located in Islamabad (540 m above sea level), Sost (2800 m above sea level), and at the Khunjerab Pass (4693 m above sea level). Calculated emission factors for carbon monoxide, hydrocar-bons, and nitrogen oxides from heavy-duty trucks in Islamabad were 12.94 +/- 1.46, 15.21 +/- 1.67, and 10.69 +/- 1.34 g km -1 (95% confidence level), respectively, for pre-Pak-II trucks, and 12.75 +/- 2.80, 14.24 +/- 3.53, and 10.24 +/- 2.34 g km -1 (95% confidence level), respectively, for Pak-II trucks, representing 2-20 times higher values than the emission standards in Pakistan and India. An altitude increase of approximately 4000 m, with the associated changes in meteorology and fleet characteristics, induced an average increase of 103.6%, 86.3%, 124.5%, and 133.6% in the emission factors of carbon monoxide, hy-drocarbons, nitrogen oxides, and carbon dioxide, respectively. Moreover, on-road emissions along the CPEC were mainly influenced by truck types. This study will support the budget evaluation of transport emissions from the CPEC trade fleet. (c) 2022 The Authors. Published by Elsevier B.V. on behalf of Chinese Society for Environmental Sciences, Harbin Institute of Technology, Chinese Research Academy of Environmental Sciences. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

Recent emissions from freight transport in Pakistan, especially along the China-Pakistan Economic Corridor (CPEC), have raised concerns about air quality. This study measured truck emissions in different locations along the CPEC routes and found that they exceeded the emission standards in Pakistan and India. The study also concluded that altitude and truck types were factors influencing on-road emissions.