International Choice Modelling Conference, International Choice Modelling Conference 2017

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Stated preferences for motorized emission reduction attributes in Kenya: an account of model performance and individual heterogeneity
Hilary Kaburi Ndambiri

Last modified: 28 March 2017


Motorized emissions are substances generated by fuel combustion and evaporation from motor vehicles. Common motorized emissions include carbon monoxide (CO), oxides of nitrogen (NOx), oxides of sulphur (SOx), volatile organic compounds (VOCs), ozone (O3), lead (Pb) and particulate matter (PM) which include dust, smoke and other solid particles. These emissions are largely harmless if they are in low concentrations but, they become pollutants if their concentrations escalate to the extent that they begin to cause adverse effects on humans and the environment. Motor vehicles are estimated to produce more air pollution than any other single human activity in the world and thus, accounting for 80-90 % of total air pollutants.


The most common vehicle fuel types used are gasoline for light-duty vehicles and diesel fuel for heavy-duty vehicles. Pollutants emitted from gasoline fueled vehicles are carbon monoxide (CO), hydrocarbons (HCs) and oxides of nitrogen (NOX) while from diesel fueled vehicles include oxides of sulphur (SOx) and particulate matter (PM). While the rate of motorization has been decreasing in the industrialized countries, it has been increasing in the developing world mostly due to increased urbanization coupled with high population growth. It has been estimated that car fleet would double that of 1990 by 2020, which implies that there will be car fleet saturation, increased traffic jams and therefore, large amounts of motorized emissions by 2020.


In Kenya, the continuous increase in the number of motor vehicles in the last one decade owing to rapid urbanization, enhanced economic development and high population growth has significantly contributed to the deterioration of air quality in most urban areas. Nairobi, which is the largest town and the capital city of the Republic of Kenya, is considered as the most polluted metropolitan area in Kenya with pollutants emanating mainly from public and private transport that together account for about 90% of total emissions. Motorized emissions in this city comprise a range of pollutants that include PM, CO, SO2, NOx and a wide range of volatile organic compounds (VOCs). These pollutants have been associated with increased prevalence of respiratory and heart diseases and dark colouration of the built environment. With significant adverse effects of motorized emissions on the welfare of the people, it has become necessary for the Kenyan government to formulate policies to cut motorized emissions in the city for improved urban air quality.


Notably, the introduction and use of low emission and fuel efficient vehicles is considered as promising and a potential measure that policy makers have at their disposal for fuel use reduction and hence, cut on pollutant emissions. However, it is not well known whether motor vehicle owners in Kenya and especially in the city of Nairobi would be willing to incur additional costs to acquire these low-emission and fuel-efficient vehicles. This is because the policy research that is available thus far has only dealt with the technical aspects of measuring the concentrations of pollutants in the air leaving a dearth of knowledge on the socioeconomic aspects of the policy that may also be ef

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