© Purevento

Cleaner city air

In Kiel, six modular air filters from Purevento clean the air along the city highway. This is good news for pedestrians and motorists, as diesel driving bans have been avoided as a result.


CO2, fine dust, nitrogen oxides – every day, cars, trucks, and buses emit pollutants into the air that harm people and the environment. In congested urban areas, high nitrogen dioxide levels are particularly dangerous, as they can cause respiratory and cardiovascular diseases over the long term. When cities exceed the permissible limit for nitrogen dioxide, diesel driving bans are therefore a frequent consequence.

The individual city air purifiers can clean up to 60,000 cubic meters of air in one hour. (Photo | Purevento)

In Kiel, there was a risk of these being imposed on the Theodor-Heuss Ring highway, where the EU limit of 40 micrograms per cubic meter was significantly exceeded in 2019. The measuring stations reported an average of 56 micrograms of nitrogen oxides per cubic meter of air. At peak times, values even exceeded 120 micrograms.

The mayor of Kiel’s concern was that if only the main road were closed for diesel vehicles, this could result in traffic jams and traffic taking alternative routes through other residential districts. So the problem would only be displaced rather than fixed. So he looked for an alternative – and found it with Purevento. Six mobile air purifiers from the company have been cleaning the air on the road since October 2020.

Air purifiers for cleaner air to breathe

Robert Krüger, Managing Director and founder of Purevento, explains how the system works: “Our modular air filtration system stands on the side of the road and sucks in the polluted air on one side. In the devices, four-stage filter units remove fine dust particles and nitrogen oxides from the intake air and retain them in the system. The purified air is blown out again on the other side. As a result, residents, passers-by and cyclists in the vicinity of the city air purifiers are supplied with significantly cleaner air to breathe.” Up to 90 percent of the fine dust and 85 percent of the nitrogen oxides and ozone remain in the city air purifier. As soon as the saturation limit of the filter media is reached, they are replaced and disposed of together with the pollutants in an environmentally friendly way.

The individual city air purifiers can clean up to 60,000 cubic meters of air in one hour. Assistance is provided by two powerful centrifugal fans from ebm-papst, which are located in each of the two cleaning chambers. Krüger explains why ebm-papst was chosen: “It was important for us that the fans’ air flows remained large and stable, even if the filter media increasingly absorbed pollutants and the pressure through the filter system dropped as a result. Efficiency, volume, and control options were also decisive factors for us. Across all these parameters, ebm-papst won us over with the performance of its fans.”

“It was important for us that the fans’ air flows remained large and stable, even if the filter media increasingly absorbed pollutants”

Robert Krüger, Managing Director and founder of Purevento

After trials with various models, the choice finally fell on RadiCal fans because they offered the best combination of air performance and operating noise. Thanks to individual control, Purevento can also always adjust the air flow to suit requirements, as the amount of air purification required depends on the volume of traffic as well as wind and weather conditions.

In discussions with other cities

For Purevento, which was founded in 2017 and is based in Trittau, the project in Kiel is the first time their devices have been used in series. But Robert Krüger is confident that this is just the beginning: “We are already in talks with several cities in Germany, Europe and Asia where compliance with the limits is not guaranteed. It would be nice if we could prevent driving bans in those places too, and provide healthy air for residents.”

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