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Air purification systems for vehicles

Draw air in, kill germs – all clean!

As a result of the corona crisis, the issue of air quality is once again gaining in importance, including for vehicle manufacturers and suppliers. Innovative solutions are required, particularly on buses and trains, so that people can travel again without having to think twice.

Nitrogen oxides, pollen, viruses – our air seems to be getting more and more dangerous. Ever since the emissions scandal, the issue of air quality has increasingly been a focal point for the automotive industry, and since the start of the corona pandemic, there has been an increase in the demand for air filters and air purification systems.

Vehicle manufacturers and suppliers are responding to this: Daimler Buses has been installing new active filters as standard in its buses since the start of this year. Volvo has announced an electrostatic filter for its cars that traps the smallest particles. Geely now offers filters for numerous models that it says will protect against viruses. Tesla will install a filter on request that is even supposed to protect against bioweapons. And suppliers such as Mann+Hummel and Heraeus Noblelight are also providing innovative solutions.

Public transport – air quality is essential

Mitchell Johnson
Good air on the bus? Whether people return to public transport in their droves or not is also dependent on how much they feel they can trust the air quality on buses and trains (Photo: Mitchell Johnson Unsplash)

Ensuring good air quality is essential on public transport, even more so than in cars or car sharing vehicles. ‘Boarding a bus, train or plane in the current climate often makes people feel uneasy. Passengers are unsure about sitting in a confined space with other people, and sometimes justifiably so’, says Erich Siebein, sales engineer at CleanTec Lighting. The Leipzig-based company specialises in innovative applications of light with a focus on the development of air disinfection and lighting systems. And it was doing so well before the start of the corona pandemic.

Since 2015, CleanTec Lighting has been working on combating airborne pathogens, i.e. viruses, bacteria, yeast fungi and spores. Its patented and accredited system “CleanTec Air!” kills 90 to 99.9 per cent of pathogens using UVC radiation. Solutions include stationary devices for rooms, doctors’ surgeries and railway stations as well as mobile devices for transportation systems and customised designs to suit customer requirements.

Disinfection by radiation

Relying on filtering with UV light: engineer Erich Siebein (l.) and CleanTec Lighting (photo: CleanTec Lighting)

‘UVC radiation is a high-energy light used to disinfect surfaces and the air. Its effect has been known for a long time and has been used for many years in the purification of drinking water, air purification in hospitals and airport terminals or to disinfect packaging’, explains Siebein. The devices suck in the ambient air, sterilise it using radiation inside the device and release it back into the room. This ensures that the air is constantly being circulated. And at up to 2500 cubic metres per hour.

‘The global coronavirus pandemic has reinforced how important and necessary hygiene is’, states Tommy Chen, developer and product manager at lighting specialist Osram. Their new development, Air Zing Mini, uses UVA light and an innovative new material: titanium dioxide coatings. The device draws in air and passes it through a titanium oxide filter. UVA light shines on the filter and activates it. A photocatalytic reaction then takes place that kills virus and bacteria cells. The purified air is then expelled through the top of the housing.

‘The greatest challenge in development was a very tight timeframe following the outbreak of coronavirus and start of the pandemic. But we managed to develop the Air Zing Mini in a short space of time and have been able to supply it to England, Germany, Russia, China, the USA and other countries around the world since the autumn of 2020.’

Tommy Chen

Production with industry experts

CleanTec Lighting has also noticed the increased demand. ‘We’re currently in talks with a Swiss and a French train manufacturer, are designing sample seats for lorries together with a seat manufacturer and also advising individual taxi companies. We are also developing concepts for a concert hall in Leipzig and for Heidenheim University’, explains Siebein.

For Siebein, a fundamental aspect of these efforts is to enable passengers and staff to once again board buses or trains without hesitation. ‘Just a year ago we were all talking about the mobility revolution, then along came corona and everyone went back to using their cars. That needs to change again’, he adds. Some transport companies, such as Hanauer Straßenbahn and Padersprinter in Paderborn, have already responded and equipped their bus fleets with a UVC device or antiviral filter.

In addition to permanently installed devices, CleanTec Air’s mobile devices are also particularly suitable for use on trains, buses or in private cars. ‘Our mobile unit can be permanently installed e.g. under passenger seats or simply ported around. From the office and the car to the bedroom – that’s what I plan to do with my own device too’, explains Siebein. They are produced in collaboration with certified experts from the industry. In the rail sector, for example, CleanTec Lighting works Photon Meissener Technologies GmbH from Saxony, whereas in the automotive sector, it works with EDAG Engineering GmbH in Bavaria. The biggest challenge here is that the devices must be as small as possible while also remaining robust.

New standards for the mobility revolution

In contrast to filters, Siebein sees light-based air purification systems as having a clear advantage: ‘It takes a very good filter to catch even the smallest viruses. And even a good filter needs to be changed frequently. This not only results in follow-up costs but also allows the collected pathogens to escape from the venting chambers into the air when changing the filter. Our UVC unit can operate for 9000 hours, run without chemicals and is much more climate-friendly’.

Whether filters or a light system, what we really need, he says, is an awareness of air quality. ‘There have been specifications and laws covering soil and water quality for many years now, but when it comes to air, there are at most a few rules about particulate matter. There are no specifications regarding viruses and pathogens. With coronavirus, however, we have been able to experience how quickly such a virus spreads throughout the world and paralyses our daily lives’. He calls on politicians to demand and promote the technical possibilities – and set new standards. And Siebein is certain of one thing: ‘The mobility revolution can only be achieved if we install air purification systems on public transport as standard!’.

‘It was important to Hanauer Straßenbahn to act proactively, go beyond the strict pandemic-related rules and not to wait until as many people as possible had been vaccinated. So far, we have equipped 15 buses and thus almost a quarter of our fleet with UVC technology’

Joachim Haas-Feldmann

‘New active filters enhance the results for air-conditioning systems of Mercedes-Benz buses. These high-performance particle filters also have an antiviral functional layer that filters the finest aerosols. With these, the critical level of 3000 aerosols that is believed to lead to infection is not reached even after four hours on the bus’

Gustav Tuschen

‘Our results show that professional devices are very good at minimising indoor aerosol particle concentrations. In cars, you can achieve a lot of air exchange via ventilation, which means that it is not absolutely necessary to have these devices in cars to prevent indirect infections’

Prof. Christian J. Kähler

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