Diesel adulteration is a problem in Zimbabwe. Industry experts estimate that a large percentage of diesel is adulterated. LPG/ CNG on the other hand can only be stored in high –pressure skids-eliminating the risk of adulteration.

Adulteration increases the tailpipe emissions of harmful pollutants from vehicles. These leads to this study, which tends to show the rate of emission of CO (carbon II oxide) and PM (Particulate matters) from engines when they are run on adulterated fuel.

Most developing country governments have not yet established a monitoring regime and system of fines that can act as a strong deterrent to fuel adulteration. There are number of reasons for this, including poor governance, a lack of political will, lack of public awareness, weak regulatory agencies and a shortage or even absence of technical staff and equipment for designing and conducting monitoring.

Given these limitations, identifying and dealing with this abuse will require addressing problems on multiple fronts.

The primary factors encouraging the practice of adulteration are the following


• Existence of differential tax levels amongst the base fuels, intermediate products and
byproducts. The adulterants being taxed lower than the base fuels give monetary benefits
when mixed with replacing a proportion of the base fuels.

• Differential pricing mechanism of fuels and adulterants and easy availability of adulterants in the market.

• Lack of monitoring and consumers awareness.

• Lack of transparency and uncontrolled regulations in the production-supply and marketing
chain for intermediates and byproducts of refineries.
• Non-availability of mechanism and instruments for spot-checking the quality of fuels.

Adulteration and emissions


Fuel adulteration causes marked effect on the tailpipe emissions of vehicles, as adulterants alter the chemistry of the base fuel rendering its quality inferior to the required commensurate fuel quality for the vehicles. This in turn affects the combustion dynamics inside the combustion chamber of vehicles increasing the emissions of harmful pollutants significantly. In some cases effects of adulteration are indirect; for
example, large scale diversion of rationed kerosene subsidized for household use to the diesel sector for mixing with diesel not only hamper engine performance of diesel vehicles, but also deprives the poor of kerosene which can otherwise be used for cooking and as a consequence of lack of availability of subsidized kerosene force the poor to continue to use biomass which expose them to high levels of indoor pollution.

Adulterated fuel increases tailpipe emissions of hydrocarbons (HC), carbon monoxide (CO), oxides of nitrogen (NOx) and particulate matter (PM). Air toxin emissions, which fall into the category of unregulated emissions, of primary concern are benzene and polyaromatic hydrocarbons (PAHs), both well known carcinogens. Kerosene is more difficult to burn than gasoline; its addition results in higher levels of HC, CO and PM emissions even from catalyst-equipped cars. The higher sulfur level of kerosene is another issue.

The consequences to long term air pollution, quality of life and effect on health are simply ignored. Also ignored are the reduced life of vehicle engine and higher maintenance costs, particularly if the taxi, autorickshaw or truck is being rented for a daily fee.