In Blog
Blog post by Joonas Vanhanen, CTO, Airmodus
First published January 18th 2018 on LinkedIn by J. Vanhanen

Topi Rönkkö, Tampere University of Technology, together with his colleagues showed that traffic is a source for small nanoparticles (link to this study further down). They call them nano cluster aerosol (NCA). The size of these particles is between 1.3-3.0 nm in diameter. Similar results are supported also by other researchers (see the links below). Atmospheric measurements near traffic show that per kg of fuel, traffic emits about 2-3*10^15 NCA. If we take the average passenger cars fuel consumption in Finland, the emissions per kilometre would be in the range of 10^14 NCA particles. And this would only be for the particles in the size range of 1.3-3.0 nm! To put this into perspective, the EURO 6 limit for solid particles above 23 nm in diameter is 6*10^11#/km. Even though the NCA measurements include both solid and liquid particles, these NCA emission levels are 100-1000 x higher than the regulatory level. And we must keep in mind that the car fleet in Finland isn’t that old and most cars probably still fulfil the EURO 6. Which cars are the high emitters for NCA is still unknown, so I am looking forward for the future research on this topic!

Further reading:
Rönkkö et al. 2017
Giechaskiel et al. 2017

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