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Modern vehicles vs toxicology

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Exhaust emissions — fuel alternatives and toxicology

A lot of research followed by industrial innovations and stricter regulations have reduced urban pollution in many European cities. But the last few months have shown us what clean air really means and that we ought to do even better. 

Regulations, and development due to the regulations, have decreased vehicle emissions remarkably. Still modern cars emit toxic compounds. Surprisingly, gasoline cars can be worse than modern diesel vehicles: for example modern gasoline engines produce similar or higher nano sized particle emissions compared to diesel engines.

A multidisciplinary group of researchers measured the exhaust emissions and performed toxicological evaluation of the exhaust of cars compliant with modern vehicle emission regulations. Euro 6a cars were fuelled with different fuels—EN590 diesel, compressed natural gas, gasoline with 10% ethanol (E10) and high-blend ethanol fuel (E85) with 83/17% ethanol-gasoline-ratio. The cars were driven on a dynamometer at -7°C and the emissions were thoroughly monitored and analysed, and aerosol particle samples collected for further toxicological studies. 

For many of the studied compounds, gasoline produced higher concentrations than the other fuels. The researchers also found for example that the amount of ethanol mixed with gasoline affects the number size distribution of the emitted particles: “The PM mass from the exhaust of E85 fuelled car were 30% lower than from E10 but the difference between PN numbers were negligible, indicating that E85 combustion produces overall smaller particles than E10.”

Using the sampled aerosol particles mouse macrophages were exposed to doses representing real exposure close to traffic and several different toxicological endpoints were studied: 

“In cars compliant with the new regulations, gasoline displayed the highest PM concentrations and toxicological responses, while the higher ethanol blend resulted in slightly lower exhaust gas PM concentrations and notably lower toxicological responses in comparison. Engines powered by modern diesel and compressed natural gas yielded the lowest PM concentrations and toxicological responses.”

In their publication the researchers also present some ways to reduce the health effects – some of which might prove to be remedies with respect to air pollution as well.

Please read the full article for details:
Hakkarainen, H., Aakko-Saksa, P., Sainio, M. et al. Toxicological evaluation of exhaust emissions from light-duty vehicles using different fuel alternatives in sub-freezing conditions. Part Fibre Toxicol 17, 17 (2020).

For a selection of other vehicle emission related publications, please visit

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