Polyphenol filters—the ultimate weapon against allergens?

Polyphenol filters are quite a bit more expensive than activated carbon cabin air filters—but it is claimed that they keep more than 90 per cent of allergens out of the cabin. So is the extra expense worth it? Can the filters live up to this promise?

Polyphenols are phytochemicals—natural aromatic compounds found in grapes, pomegranates, ginkgo, and tea, for example. They have an anti-inflammatory and anti-carcinogenic effect, reduce fatty deposits in blood vessels, and lower the risk of developing Alzheimer’s disease. So polyphenols are truly an all-round weapon that helps protect against all kinds of diseases.

Cabin air filters equipped with a special polyphenol coating have been available on the market for some time now. They aim to prevent the growth of micro-organisms and keep allergens out of the cabin. So, should you try these filters for the sake of your health? Or are manufacturers simply using the good reputation of polyphenols to encourage us to dig deeper into our wallets?

In order to answer these questions, we first need to briefly clarify what allergens actually are. They can be divided into three groups: Cross-reactive allergens such as house dust mites can irritate mucous membranes. Contact allergens such as chromium or nickel can cause skin rashes. And lastly aeroallergens—such as birch pollen, fungal spores, or plastic vapours—can lead to breathlessness. Usually, allergens have no particular effect on humans; however, they trigger allergies in some people.

Polyphenol filters could therefore be useful if you suffer from allergies, or want to prevent them. We subjected the filters to extensive tests in the laboratory using standard germs (Micrococcus luteus, which belongs to the germ group and Aspergillus niger, which belongs to the fungal group). The result: the already fairly general promises made by the manufacturers could not be fulfilled. Not only the germs but also the fungi had spread in the polyphenol filter material examined—the filter medium was completely overgrown with fungi in particular.

Conclusion: pay attention to the price-performance ratio. MAHLE develops both HVAC systems and cabin air filters in close coordination with original equipment manufacturers. Our high-quality activated carbon cabin air filters not only reliably filter almost 100 per cent of all solids such as dust, pollen, and spores from the air but also keep the cabin free of gases, vapours, and odours. However, like all cabin air filters, they can only handle their task reliably if replaced on a regular basis. We recommend every 20,000 km or once a year.

Fungal growth


Germ growth