Inflammatory potential of low doses of airborne fungi from fungal infested damp and dry gypsum boards

- A J-shaped dose-response curve was found for fungi vs. inflammatory potential.
- Aerosols from dried out and damp gypsum boards were inflammogen.
- Aerosols were dominated by Penicillium chrysogenum and Aspergillus versicolor.
- Bacteria were present on the surfaces, but not in the aerosols.
- More research on inflammation of low concentration fungal samples are needed.

This study has investigated the total inflammatory potential (TIP) of low concentration fungal samples from moisture-damaged and fungal infested gypsum boards. The fungal aerosols were generated from damp and dried surfaces, and sampled using filter sampling and liquid impingement. The TIP of the samples was analysed using a granulocyte assay based on differentiated HL60 cells. The study found a tendency to a J-shaped dose-response curve for fungal samples. Low concentrations of fungi were aerosolised from the gypsum boards, and the aerosols were dominated by Aspergillus versicolor and Penicillium chrysogenum. Bacillus infantis and Paenibacillus sp. were found on the gypsum boards, but not recovered in the aerosols. A significant correlation was found between the TIP of diluted and undiluted samples of fungal aerosols. However, diluted samples had a higher TIP than undiluted samples, and no significant association was found between concentration of fungi and the TIP of the samples. This is likely due to the J-shaped dose response curve. The aerosol samples from the dried gypsum boards had a significantly higher TIP compared to aerosols from the damp surfaces. However, the J-shaped dose-response curve weakens the conclusion on the influence of surfaces dampness, sampling time, fungal species or sampling methods. It could, however, be concluded that samples from both damp and dry surfaces induce inflammation in the HL60 cells, despite the low concentration of fungi. Thus, a dried fungal infestation in a building seem still to present a concern for the occupant.