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Outdoor air purifiers

Outdoor air purifiers

Worldwide many city residents suffer from breathing in the high concentration of pollutants found in the ambient air.

Filter Cubes: Our outdoor air purifiers against air pollution

The challenge – polluted air in cities

Sources such as traffic and industry cause high concentrations of particulate matter and nitrogen dioxide (NO2). In Germany and other countries, the exceedances of limit values are a constant source of discussion. In high traffic areas or places with large emissions and low air exchange, the exposure is especially high and the effect on human health is harmful.

This applies, for example, to busy streets and subway stations. People with respiratory illnesses, the elderly or children should not be exposed to high concentrations of particulate matter or nitrogen dioxide. Surrounding yourself with clean air is a quality of life necessity. In places where people are studying, working, shopping or spending their free time, it is important to be surrounded by clean air.

"Three main pollutants cause significant damage
Poor air quality continues to damage European's health, especially in urban areas, with particulate matter (PM), nitrogen dioxide (NO2) and ground-level ozone (O3) causing the biggest harm."

European Environment Agency; Air Quality in Europe, Report 2018

Our solutions provide clean air at pollution hotspots

Filter Cubes

Watch the video and see how it works

The modular MANN+HUMMEL Filter Cube helps to improve air quality in places with high air pollution - such as traffic junctions or busy roads. Even in particularly sensitive areas such as schoolyards, playgrounds or food courts, the use of Filter Cubes helps to efficiently reduce air pollutants. The Filter Cube technology can also be integrated into existing infrastructure such as bus stops or billboards (see Filter Grid and Filter Square).
The decentrally applicable Filter Cubes are able to bind more than 80 percent of the nitrogen dioxide (NO2), ozone (O3) and fine dust contained in the ambient air that is drawn in. The core of the technology is a newly developed combifilter, which includes a filter layer that retains particulate matter. Due to the large surface area of the additional highly porous activated carbon media, NO2 and O3 is adsorbed very effectively at particularly low pressure drop and energy consumption.

Depending on the requirements, using a modular system means a number of Filter Cubes can be installed on top of each other to form a filter column. A filter column with three Filter Cubes is able to clean 14,500 m3 of air every hour. The Filter Cubes are equipped with an intelligent mechatronic system architecture. Available sensors record air and weather data as well as the pollution level and transfer the data to a cloud. This way the filter system controls itself depending on operating and environmental boundary conditions and thus saves energy costs since the fan is only running when it is needed.

Scientifically proven effectiveness of Filter Cubes

Already in 2018, the effectiveness of MANN+HUMMEL Filter Cubes was confirmed in a joint study with KIT (Karlsruhe Institute of Technology). Meanwhile the effectiveness of a large-area installation of filter columns has been proven in long-term tests at the Neckartor in Stuttgart, Germany. This heavily frequented main road was for a long period of time one of the most polluted places in Germany by fine dust and harmful gases. More detailed information on the procedure and test setup can be found in the final report of the pilot project, which was prepared in consultation with the Baden-Württemberg Ministry of Transport.

Compared to other measures from cities' air pollution control plans, the installation of a Filter Cube network has been more successful than average. Actions such as converting the vehicle fleet to e-vehicles, expanding and promoting bicycle traffic and public transport, software updates and traffic management are all in the very low single-digit range in terms of nitrogen dioxide reduction. Only driving bans would be roughly equivalent to the effectiveness of the Filter Cubes, but they not only severely restrict delivery and commuter traffic, but also keep consumers away from city centers. Since the Filter Cubes clean the air without affecting the traffic flow, they are economy-friendly and at the same time protect residents and passers-by.

Exemplary process of Filter Cube installation

The first step of the project is the investigation of the surrounding area, which has particularly high levels of pollutants. Whether it is an open area on a busy road, an inner courtyard of a business district or a relatively closed subway station, our experts make calculations for each of these conditions and consider different measures. They check where the fine dust and NO2 pollution is highest and how the pollutants are spread through the air. Afterwards they determine how many Filter Cubes are needed and where they should be installed in the respective area. With the help of a simulation, these plans are determined internally and then checked by an independent engineering office.

A Filter Cube requires 1 m2 of space and access to electricity. Depending on the location and customer requirements, a foundation and a data connection can be included. After the preparation of the infrastructure has been completed on site, the installation of the systems can begin. Thanks to an intelligent system architecture, the Filter Cube controls itself depending on the operating and ambient conditions. However, the operator can also control the units by remote control and access the system as required.


Reference projects


General Information

Critical values for particulate matter and nitrogen dioxide are being exceeded in many German cities, affecting the health of city dwellers. MANN+HUMMEL has developed Filter Cubes to reduce the concentration of pollutants in places with particularly polluted air. These are capable of extracting 80 percent of fine dust and nitrogen dioxide from the attracted ambient air with very low energy requirements.

As part of a pilot project, the first Filter Cube columns were installed at Stuttgart's Neckartor in November 2018 to protect residents and avoid driving bans. Following positive results in reducing fine dust pollution, MANN+HUMMEL retrofitted the existing constructions with newly developed combifilters in July 2019. These enable the capture of not only fine dust particles but also nitrogen dioxide from the air.

Thanks to the successful pilot project at the Neckartor, MANN+HUMMEL is the first company that has scientifically proven the effect of the Filter Cubes. This verification was produced in cooperation with the Karlsruhe Institute of Technology and the State Environmental Agency of Baden Württemberg.

Meanwhile, we installed and commissioned 15 projects on 3 continents and cleaned 1.640.000m3 / hour of air outdoors. To put that into perspective, this is the amount of air needed to cover the air demand of 3.420.000 people per hour.

Equipped with energy-efficient fans, the Filter Cubes attract ambient air. This air is filtered with the aid of fine dust particle filters, removing dangerous fine dust particles from the attracted ambient air. If the values of nitrogen dioxide or ozone are also too high, so-called combination filters are used. These have a highly effective filter layer for fine dust combined with a special activated carbon layer. Due to its large inner surface, the highly porous activated carbon is able to absorb NO2 very efficiently.  This specially developed combination filter medium enables a particularly high air throughput with very low energy consumption at the same time. This purifies the air with very low energy consumption.

The operation of the filter columns can be adjusted as required via a control unit and thus react to the current air quality. External sensors record air and weather data, which are then merged and analyzed in a cloud.
The effective radius of a column is 15-20 meters. In order to achieve an area-wide effect within a certain road section, we need a network of several columns in which the effective radii overlap. Thus a filtration field can reduce the air pollutants fine dust and NO2 in the person-relevant area (e.g. footpaths) by up to 10-30%.

According to the WHO, around 4.2 million people die each year worldwide from outdoor air pollution. The main cause is fine dust (particulate matter), which can penetrate deep into the lungs and cause disease (see graph on the left: Which particle sizes are dangerous for our body).

Nitrogen dioxide worsens allergies, damages the respiratory tract and can contribute to heart disease.

Fine dust pollution is particularly relevant at particular locations within cities. Very often, these higher emissions can be found at points where more people tend to be. This is true for large road junctions, subway stations, bus stops, or underpasses. The risks to health at these locations are especially high.

For certain groups, the risks from pollutants are above average. People with respiratory diseases, elderly people, or children should not be exposed to increased concentrations of fine dust or nitrogen dioxide.

Clean air is a basic requirement for quality of life. Wherever people study, work, shop, or spend their leisure time, they want to be surrounded by clean air. No one wants to be concerned about fine dust values.

Construction, costs, electricity

If only the reduction of fine dust from the ambient air is required, particle filters made of highly developed microfiber media are used. At traffic junctions with a high nitrogen dioxide load, so-called combi-filters are used, which have a special activated carbon layer in addition to a highly effective filter layer for fine dust. This layer separates the NO2 from the ambient air by physical adsorption, chemical binding and catalytic reduction.

Each Filter Cube installation is unique, so we cannot mention standard prices. The design (Filter Cube I, II, III) and number of Filter Cubes depend on numerous factors, such as location, pollution, wind conditions, etc. For specific inquiries, please get in touch with the contact persons at the bottom of the page. They will provide you with information specific to your project description.

The energy consumption of our Filter Cubes III is approx. 1.500 W/h. This is comparable to a commercial vacuum cleaner, but with 100 times the air throughput.

The filter columns require a power connection and cannot be operated independently, for example by fuel cells.

The air volume flow of a Cube III column is 14.500 m3/h. This corresponds to a room the size of a football field with a height of two meters.

A Filter Cube III weighs about 1.000 kilograms.

The filter columns are 3.60 meters high, have a footprint of less than 1 m2 and each consist of up to three stacked components, the cubes. The individual cubes have a side length of almost one meter.

The filters are disposed of as household waste in accordance with existing regulations. It is not hazardous waste because the fine dust bound in the filter is no longer harmful to health.

We want to achieve a reduction in particulate matter and nitrogen dioxide pollution at particularly polluted locations. Using modern separation and catalyst technologies, waste incineration plants in Germany capture hazardous pollutants such as nitrogen dioxide and particulate matter on a large industrial scale in accordance with environmental regulations. What remains at the end is ash that can be deposited in landfills.

Effect and Evidence

The effective radius of a column is 15-20 meters. In order to achieve an area-wide effect within a certain road section, we need a network of several columns with overlapping effective radii. Thus a filtration field can reduce the air pollutants of fine dust and NO2 in the person-relevant area (e.g. footpaths) by up to 10-30%.

Thanks to the pilot project at the Neckartor in Stuttgart, MANN+HUMMEL is the first company that has been able to prove this effect scientifically in cooperation with KIT and LUBW.

Residents and Politics

Depending on the installation area, different requirements apply with regard to noise protection. These are defined in a national Technical Instructions for Noise Protection (TA-Lärm). Our filter cubes comply with the TA noise.

Depending on their location and proximity to residential buildings, individual filters are regulated up or down according to the legal requirements.

We also use technology for sound insulation. We benefit from our acoustics laboratory and our expertise in sound design, which we have gained in the automotive industry.

The measuring stations are installed where the exposure to air pollutants is particularly high. The risk to the health of residents, pedestrians and road users is correspondingly high at these locations. The Filter Cubes from MANN+HUMMEL improve air quality along the road sections where they are positioned. There is no specific and punctual influence on the measuring points.

The MANN+HUMMEL filter columns are part of an overall solution for improving the air quality of the respective cities. Together with other measures anchored in their air pollution control plans, our columns can offer effective protection against particulate matter and nitrogen oxide at particularly polluted locations.

Further fields of application

In places with high emission levels and low air exchange, such as underground stations, human health is particularly at risk. In bus stops or train stations, people are exposed to temporarily polluted air. Here our technology could also be used to improve the air and thus protect the health of passers-by. Various Filter Cube projects are in the planning and implementation stages. In addition, our developers are working on further applications for food courts, hotel lobbies, airport halls and sports sites, among others, and on the integration of the technology into existing infrastructures.

Our whole portfolio for better air quality in cities

Filter Cubes

The modular MANN+HUMMEL Filter Cube helps to improve air quality in places with high air pollution and can also be integrated into existing infrastructure (see Filter Grid and Filter Square).

Filter Grid

The technology can also be integrated into billboards for bus stop shelters, train stations or in any other custom-built designs and available infrastructure.

Filter Squares

MANN+HUMMEL has developed so called Filter Squares which are especially tailored for use in underground stations.

Rooftop Particle Filter

The newly developed fine dust particle filter from MANN+HUMMEL improves the emission balance of vehicles by capturing emissions from the vehicle and filtering fine dust from the ambient air.

Underfloor Particle Filter

The newly developed fine dust particle filter from MANN+HUMMEL improves the emission balance of vehicles by capturing emissions from the vehicle and filtering fine dust from the ambient air.

Brake Dust Particle Filter

In cooperation with its development partner Hitachi Automotive Systems, MANN+HUMMEL has made substantial progress with its brake dust particle filter - also towards better air quality.

Frontend Particle Filter

As an extension of the wide range of initiatives aiming to reduce fine dust pollution, MANN+HUMMEL has developed a world premiere in cooperation with HBPO.

Contact persons

Thomas Michalak

Thomas Michalak

Sales & Business Development Manager - Public Air Solutions