Improvement of Air Quality in Vehicle Cabins by Nanoparticle Filtration

A filter system is presented which allows the reduction of the concentration of ultrafine particles in vehicle cabins to very low levels. The original ventilation system is switched to the recirculation mode and all cabin intake air is supplied via a retrofitted filter system. Tests with a variety of different vehicles (from passenger cars to coaches) show the efficiency of the system. Filters incorporated in present ventilation systems remove large particles, for example pollen, but usually are inefficient for removing very small particles. This is demonstrated by Fig. 1, where the particle number concentration outside and inside a car is plotted during a journey near Zurich. It is obvious that the concentrations inside and outside are more or less identical. All windows were closed during this measurement. Tests with a number of different all cars showed similar results. The filters included in today’s ventilation systems usually cannot remove nanoparticles, and so vehicle cabin indoor and outdoor nanoparticle concentrations are more or less identical. The nanocleaner, consisting of a very efficient filter and a high performance blower, allows reduction of the particle concentration in the cabin from several hundreds of thousands or millions per cc. to a few thousand per cc., equivalent to remote woodland, the total exposed dose being reduced by some two orders of magnitude.