AIR POLLUTION FROM DIESEL VEHICLES IN QATAR: ASSESSMENT, PROJECTION AND MITIGATION

Abstract

Abstract Road traffic is one of the main sources of particulate matter (PM) and gaseous emissions in the atmosphere. In order to propose effective mitigation scenarios, the proportions of PM traffic emissions, whether they are exhaust or non-exhaust emissions, should be evaluated for any given geographical location. In the first part of this work, we reported on the evaluation of particulate matter emissions from all registered heavy-duty diesel vehicles in Qatar. Moreover, in situ elemental composition analysis was conducted for side and main road traffic dust, and compared with non-traffic PM. The results were used for the evaluation of the enrichment factor and preliminary source apportionment. The enrichment factor relates the concentration of an element in PM to its average concentration naturally existing in the earth’s continental crust. A novel method for source apportionment was developed based on the elemental finger print of the PM composition. The enrichment factor of anthropogenic elements amounted to 350. The traffic source based on sulfur elemental fingerprint was almost 5 times higher in main roads compared with the samples from non-traffic locations. Moreover, PM exhaust and non-exhaust emissions (tyre wear, brake wear and road dust resuspension) were evaluated. It was found that the majority of the dust was generated from tyre wear with 33% followed by road dust resuspension (31%), brake wear (19%), and then exhaust emissions with 17%. The low contribution of exhaust PM emissions were due to the fact that the majority of the registered vehicle models were recently made and equipped with efficient exhaust PM reduction technologies. The second part of this research involved the assessment of the life cycle of diesel fuel in all registered non-passenger vehicles in Qatar as of November 2017. The Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model was used as a source of normalized data to evaluate diesel fuel emissions for all non-passenger vehicle categories. This work aims at estimating the emissions from all non-passenger diesel vehicles in Qatar and evaluating the impact of the fuel life cycle assessment. The emissions of CO2, NOx, CO, SO2, VOC, black carbon (BC), organic carbon, fine particulates PM2.5, and coarse particulates PM10 were evaluated. SO2 emissions were found to be dominant during the well to pump (WTP) stage of the life cycle assessment (LCA) process, while the pump to wheel (PTW) stage was found to be dominated by CO, VOC, PM10, PM2.5, and BC emissions. NOx and organic carbon emissions were virtually the same during both stages. Total greenhouse gas emissions amounted to 5367 kt of CO2 equivalent (CO2-eq) in 2017 as compared with that in 2014 (5277 kt), the only reported value in Qatar for transportation emissions. In addition, several mitigation strategies were proposed to ensure sustainability in the transport sector and to minimize the negative impact of diesel fuel emissions in the country such as using clean fuel, reducing vehicle kilometers traveled, encouraging car pooling and the use of metro and public transportation, electrification of vehicles, improvements in vehicle design to reduce fuel consumption, in addition to planting trees and development of green structures as barriers to traffic emissions in urban cities. To this end, the actual data on the diesel vehicle count from the traffic department was used along with the annual travelled distance to calculate the actual emissions for diesel fleet in Qatar in 2017. The projection of diesel fleet in 2030 was then estimated based on three scenarios: (1) if fleet growth rate continued on the same trend as per the historical data; (2) if the rate increased 10% based on 2017 count; and (3) if there was a decline in the growth rate of vehicle count by 20%. The annual projected CO2 emissions amounted to 4171, 1800 and 1750 kt for the three scenarios; respectively. Similarly, the annual projected NOx emissions were about 100, 43 and 42 tons for the three scenarios; respectively. The results showed that, if no policy is put in place, there will be around 170,000 diesel vehicles contributing to huge amounts of particulate and gaseous emissions. However, under the current plans of the electrification of 5% of cars and 25% of public buses, 10% and 5% reduction in CO2 and NOx emissions will be attained; respectively. The impact of electrification to this category is not as significant as it could be since the majority emissions are due to heavy duty vehicles which are not impacted by this policy.

Date of Award	2021
Original language	American English
Awarding Institution	HBKU College of Science and Engineering