In December 2018, 17 filter columns from Ludwigsburg-based MANN+HUMMEL were installed at Stuttgart’s Neckartor road junction, one of the most heavily polluted streets in Germany with fine dust and nitrogen oxides. The three filters installed in each column initially reduced the concentration of PM10 (fine dust particles with a diameter of less than ten micrometers). In February 2019, newly developed combifilters were retrofitted on a trial basis which, in addition to PM10, also remove nitrogen dioxide (NO2) from the air via an activated carbon insert. These filters have now been replaced by new models with a larger filter surface area and more powerful fans, which are expected to boost efficiency.

The filter columns now suck in up to 14,500 cubic meters of air per hour and bind more than 80% of the PM10 and nitrogen dioxide contained in the ambient air they draw in. Sensors and control electronics ensure that the systems switch on only when the specified pollutant limit values are reached. MANN+HUMMEL expects that the use of the new systems will lead to a reduction of between 10 and 30% in the concentration of nitrogen dioxide in the air.