Filters of automobile air conditioning systems as in-car source of exposure to infections and toxic moulds

Abstract

The main component of an air conditioning system is air filters. Over time, the filters of an air conditioning system in cars can turn into sources of emission of microbiological hazards. The aim of this study was to quantitatively and qualitatively assess the presence of infectious and toxic fungi in the AC filters in passenger cars. The studied non-woven filters were removed from passenger cars during the "winter"/"summer" seasons. The taxonomic identification of the fungi isolated from the filters was performed using both the culture-based and molecular methods. RT-PCR was applied to assess the presence of gene fragments regulating aflatoxin biosynthesis in the isolates obtained from fungal cultures. The average fungal concentrations in the filter samples collected during the summer/winter season were 5.4 × 10⁴ cfu/m² and 2.4 × 10⁴ cfu/m², respectively. Most of the filter samples, collected in both the studied seasons, revealed the presence of Aspergillus species including A. fumigatus, A. niger, A. terreus and/or A. flavus. The recorded levels of fungal contamination of AC filters in passenger cars indicate the necessity for more frequent filter replacement in this type of vehicle. Occupational exposure to moulds and the resulting health problems that may be experienced by professional drivers should be properly recognised in order to undertake effective preventive measures.

Keywords: Aflatoxin; Air conditioning system; Cars; Filters; Harmful biological agents; Moulds.

Fig. 1

Percentage distributions of microbial groups to the total fungal microbiota isolated from filters in the summer (a) and winter seasons (b)

Fig. 2

Scanning electron microscopy picture of Aspergillus spp. on non-woven air conditioning system filters