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The vehicle compartment air quality challenge

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Point of view of Amine Mehel – teacher researcher at ESTACA

Air quality is a public health issue that directly affects the transport industry and forces it to innovate to offer cleaner, healthier transport. To measure air quality, ESTACA researchers are studying the concentration of particles and gas pollutants; the latter should not exceed a certain threshold, outside or inside, in order to limit harm caused to health and the environment.

The estimated health cost of the impact of poor air quality (stroke, respiratory problems, cancer, the foetus) is 68 to 97 billion Euros. Pollution also affects the environment and visibility (see China).
The framework law no. 96-1236 of 30 December 1996 on Air and Rational Energy Use aims at rationalising energy use and defining a public policy that includes air in urban development issues. Everyone has the right to breathe air that is not harmful to their health.

For industrialists, there is a dual goal: controlling emissions of gas and pollutants (factories, vehicles, exhausts, etc.) and secondly, analysing the dispersion of these pollutants and their infiltration into cars, planes, metro stations, train carriages, etc. Currently, a law exists on outdoor air quality, but not yet concerning indoor air quality. Studies have nevertheless shown that the air is more polluted and hence more harmful inside vehicles than outside (cumulative effect and concentration, to which can be added emissions from the materials themselves).

This air quality issue is the same for all types of transport. For automobiles, the pollutants seep into the passenger compartment through the air vents. In rail, braking in underground stations emits pollutants that enter the carriages and then the station. In planes, the air in the cabin originates from the turbojet compressor, and is charged with harmful oil droplets. There are various means of improving indoor air quality such as charcoal filters, that filter out some gas pollutants and the HEPA (High Efficiency Particulate Air) filter that can filter out particulate pollutants, with one exception: the particles are so fine that it is difficult to filter them out and this generates additional energy consumption which is, in turn, polluting.

ESTACA Lab' has leading-edge expertise in these issues and has been working closely with industry and institutions for many years. Here are some examples:

With Toyota Motor Europe to reduce pollutants at the source of the emission: the engine (for example work on Blowby gases, recovery of oil droplets using an oil remover so they are not burned). With start-up companies on the brake and brake particle capture devices.

With the ADEME (France’s Environment and Energy agency) we are working on ventilation or flow to deflect particles. For example, we are studying air intake situations – CAPTIVH project with the aim of preventing the infiltration and cumulative effect of pollutants in the passenger compartment.

With the SNCF CIM (engineering and materials centre), we are conducting a study into brake particles, simulating the dispersion of particles in interaction with the quays and in a sealed enclosure, and then analysing how they enter the carriage.

Two theses are currently being studied at ESTACA on these issues: one with IFSTTAR (French Institute for Transport Science and Technologies, Town Planning and Networks) on the experimental study of the dispersion of nanoparticles from exhausts and the other with the LEMTA (Laboratory of Energy and Theoretical and Applied Mechanics – Lorraine University) on a digital study of the interaction between nanoparticles, exhaust flows and vehicles, a thesis being conducted jointly with the University of Bamako in Mali. The students are also examining this issue via 3rd-year PIRATE projects (Project for initiation in applied research in mentored work).

While an initial step has been taken thanks to standards limiting the concentration of pollutants, there is still no standard regarding passenger compartment infiltration and hence indoor air quality (especially for the car and rail sectors). This is the second stage that ESTACA Lab is involved in with its partners, reflecting more generally on cleaner transport for the future.