Fuel Ethers and Air Quality

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Widespread gasoline use results in certain emissions to air. While improvements in car technology have significantly reduced these emissions compared to the past, the use of fuel ethers as gasoline components contributes additionally, both directly and indirectly, to the improvement of air quality.

Direct improvement of air quality is obtained because the oxygen content of fuel ethers leads to cleaner burning of the gasoline, especially in the cold start phase of the engine. As a rule of thumb, exhaust emissions (VOCs) are reduced by the same percentage as the MTBE content in the gasoline.

In comparison to the alcohols used in their production, ethers reduce the overall vapour pressure of gasoline and the related evaporative emissions to air which causes ozone.

Another characteristic of fuel ethers is their capacity to raise the octane number in gasoline, replacing less desirable components. Raising the octane number of gasoline has allowed the development of more efficient engine technologies with lower emissions. Fuel ethers also provide the possibility for this trend to continue.

Furthermore, fuel ethers have the lowest ozone forming potential of all the oxygen containing octane boosters. They contribute to lower evaporation and permeation of high volatile organic carbons in the finished gasoline which in turn means less ozone formation. Therefore ethers help indirectly to reduce emissions of toxic substances in the air. For MTBE this is proven by ozone measurements in the US and from official evaluations by the likes of the German federal Environmental Agency (Umweltbundesamt, UBA)

A good practise standard when handling ethers and gasoline containing ethers is necessary to minimise emissions of ethers and gasoline in air. 

Further reading
Fuel Ethers improve Air Quality and reduce GHG emissions
Fuel Ethers Risk Assessments    
Fuel Ethers and REACH

Useful links
Air Quality Directive
Innovations for Greenhouse Gas Reductions: A life cycle quantification of carbon abatement solutions enabled by the chemical industry