Regardless of a vehicle’s drive system, 85 percent of fine dust in road traffic is caused by brake, tire, or road abrasion. The smallest dust particles, hardly noticeable to the naked eye, are only a few micrometers in size with a diameter of only 10 micrometers and can therefore be easily inhaled. In the past year, the World Health Organization (WHO) has recommended significantly lower particulate matter limits than in the past but according to experts, it would be impossible to comply with these new values in many urban areas in Germany.

With that in mind, Audi has now developed a filter for the front end that can collect particulate matter from its environment; it functions similarly to stationary systems that are already in use in some cities. The mobile version ensures not only are the car’s own particulate emissions absorbed, such as those of an Audi e-tron, but those of other vehicles can be absorbed as well – right where they are generated.

The filter is integrated into the vehicle’s existing airflow in front of the radiator so that only a few modifications to the car are necessary, keeping costs down. The filter element is controlled via the switchable cooling air inlet and its mechanical function is comparable to that of a vacuum cleaner. By a similar principle, the fine dust particles remain stuck in the filter and the air can still flow through it.

Thus far, the filter has been used in Audi e-tron test vehicles. While driving, it passively filters by means of the movement of the vehicle; air flows through the filter system, which captures even the smallest particles. Another possibility is filtering during stationary charging. A fan that is already built into every electric vehicle conveys ambient air through the radiator – the system takes advantage of this process and can thus actively filter the air flowing through it, using the fine dust filter, ensuring the smallest particles are absorbed, even when stationary. This is ideal for use in urban environments, where the particulate matter pollution is much higher than in rural areas.

The assessments conducted on the test vehicles were not only used to analyze the effectiveness of the filters, but also to determine whether the technology affects overall vehicle usage. After over 50,000 kilometers of endurance tests on the Audi e-tron, the answer was clear: the filters have no negative effect on the operation of the electric vehicle, including on hot summer days or during fast charging.

The system is so effective that, depending on the usage scenario, the Audi e-tron particles are completely filtered out in a highly polluted city such as Stuttgart. In polluted cities, fine dust emissions can be actively and passively absorbed by up to three vehicles in a typical customer scenario. To make the system even more efficient, Audi is working to connect it with existing sensors such as weather stations, plus they plan to develop a display logic in the vehicle, allowing passengers to determine when the system is active and how much has already been filtered.

The filter itself is easy to maintain and must only be replaced when the regular service interval has been reached. A lifecycle analysis of the entire filter system has shown that it will account for 14.9 kilograms of CO2 equivalents. Additionally, the filter itself consists of 15 percent recycled material and the entire system is 60 percent recycled.