Mycological contamination of cabin filters as a potential source of air pollution inside passenger vehicles

Abstract

Microbiological pollutants of cabin filters may affect the air quality inside vehicles. The main aim of the study was to evaluate cabin filters in terms of their effectiveness in retaining mycological contaminants. The research material consisted of 100 cabin filters obtained during periodic replacement of filters in passenger cars. Mycological contamination of filters was examined using microbiological, biochemical, immunoenzymatic and molecular methods. The average concentration of fungi in cabin filters was 7.2 × 10⁷ CFU/m², and Cladosporium, Alternaria, Penicillium, and Aspergillus genera were most often isolated. For Aspergillus species, the highest concentration reached 3.3 × 10⁷ CFU/m², with dominance of A. fumigatus. Among the Aspergillus strains tested, the presence of the aflO gene related to aflatoxin biosynthesis and the polyketide synthase gene related to ochratoxin A biosynthesis was detected. The presence of total aflatoxin (B₁, B₂, G₁, G₂) and aflatoxin B₁ was detected at levels of 5.37 µg/kg and 1.71 µg/kg for standard filters and 2.43 µg/kg and 0.65 µg/kg for carbon filters. The level of ochratoxin A contamination was 0.96 µg/kg and 0.55 µg/kg for standard and carbon filters, respectively. Aspergillus species showed high enzymatic activity of acid phosphatase, β-glucosidase, naphthol phosphohydrolase and N-acetyl-β-glucosamidase. Based on the test results regarding the concentration of mycotoxins and the effectiveness of capturing fungal conidia, it was found that carbon filters are more effective than standard filters. Recommendations for filter manufacturers and car service policies should include the use of cabin filters with a layer of activated carbon, and their regular replacement after a year of use.