Swiss scientists have tested currently produced vehicles and concluded that modern direct injection gasoline engines emit more dangerous substances than the old diesel units.
The research made by Swiss scientists from Empa (the Swiss Federal Laboratories for Materials Science and Technology) has destroyed a myth that modern gasoline engines emit less soot particles into the atmosphere than diesel ones. Moreover, these motors turned out to be dirtier than the 15-year-old diesels.
The reason for environmental unfriendliness of the modern gasoline turbo engines lies in the very principle of their work. In order to comply with strict standards of efficiency, fuel injection in them takes place under enormous pressure directly into the cylinders.
That is, there is no process of mixing fuel with air in the intake channel. As a result, some particles of gasoline do not have time to burn completely due to lack of oxygen. Thus, a cloud of ultra-fine soot particles appears, which are emitted into the atmosphere.
Modern particulate filters can cope with emission of such particles as small as 2.5 microns. But at present such filters are installed only in diesel cars. However, this situation may change from September 1, 2019, when all manufactured vehicles will have to meet more stringent European requirements of the Euro 6d-Temp emission class.
In the meantime, the direct injection gasoline engines clearly remain more dangerous in terms of emissions of the smallest solid particles than the diesel ones.
It should be understood, and this fact has already been proven: soot particles of automobile exhausts are incredibly dangerous to human health. Inhalation of them is more harmful than active smoking. Ultra-fine dust is a powerful especially destructive carcinogenic agent, since it is not filtered out by the lungs and bronchi, but directly gets into the bloodstream.