project | 12.05.2021

Testing of allergen reduction efficiency for biofunctional M+H filter media

Biogenic, airborne allergens (indoors mostly from mites, moulds and animals and outdoors mostly from grasses, trees and moulds) can put sensitised people at risk.

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©Diagram: bifa Umweltinstitut GmbH

As a rule, biogenic allergens are proteins with a structural or enzyme function. They form a very small proportion of the total protein in the allergen-producing organism. Important representatives of grass pollen (Phleum pratense Phl p 5) and house dust mite allergens (Dermatophagoides pteronyssinus Der p1) were used to test the efficiency of allergen-reducing filter fleeces.

Anti-allergenic filter media - principle of action and detection
A few picograms of allergen per m³ of air can cause allergic reactions in sensitised persons. The most important allergen sources (pollen, mite faeces) are comparatively large particles in the μm range. Standard filters can also separate correspondingly large particles from the air with high efficiency. However, these particles can release much smaller fragments with a high allergen content. Anti-allergenic filter media destroy the molecular structure of the allergen proteins and convert them into precipitated proteins without the original allergenic action potentials. Therefore, the anti-allergenic effect persists even when denatured particle fragments pass through the filter medium. This summary contains results of tests on the M+H filter medium FreciousPlus. This filter medium for passenger car cabin air filters has a biofunctional finish that binds allergens and reduces microbial growth. microbial growth. Most allergens are soluble protein molecules. Denaturing agents destroy the molecular structure of the proteins. As a result, the proteins are no longer water-soluble and they precipitate. This is confirmed by a simple screening procedure (Fig. 1): Buffered (pH 4.7) protein solution of bovine serum albumin (BSA) remains unchanged when standard filter media is added. The anti-allergenic filter media denatures the protein and produces a visible precipitate (turbidity). Allergen-producing cells contain very high amounts of protein, but only a very small proportion of this is allergenically active. The other proteins and cell components contribute to the stability of the allergen protein. A quantitative study confirmed that the allergen protein is completely precipitated by biofunctional M+H filter media even in the presence of an excess of other proteins. (Figure 2): The soluble fraction of the allergen was reduced by > 99 %.