Novel detection methods and knowledge of indoor emissions from building materials, fungi, and cleaning agents

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School of Engineering | Doctoral thesis (article-based) | Defence date: 2020-09-10
Degree programme
82 + app. 62
Aalto University publication series DOCTORAL DISSERTATIONS, 122/2020
The quality of the indoor air is paramount to guarantee occupants' health and comfort as they spend most of their time indoors. Yet, a proper understanding of emissions' mechanisms from moisture-damaged building materials and of suitable detection methods targeting harmful indoor air contaminants are lacking. This dissertation aims at providing new knowledge and methods for the detection of volatile organic compounds and microbial contaminants. The airborne emissions of C9-alcohols from DEHP-free PVC floor coverings were studied at 75, 85 and 95% RH. The aim was to determine whether C9-alcohols could be used as an indicator of the degradation of the DEHP-PVC floor coverings and of hidden underlying moisture damage. 2-ethylhexanol and TVOC emissions were also monitored. The C9-alcohols emissions were the highest at 95% RH but were also emitted at 75 and 85% RH. It was concluded that monitoring C9-alcohols alone were not a clear indicator of the hidden degradation of floor coverings. The toxin production of toxigenic Trichoderma strains isolated from buildings where occupants reported health symptoms was investigated. The toxicity profiles of the exudates and biomass extracts were similar to reference peptaibols (alamethicin and trilongins). The toxins were identified as trichorzianines, trilongins, trichostrigocins and trichostrigocin-like peptaibols using HPLC/ESI-MS/MS. Furthermore, the Trichoderma strains emitted the same toxic peptaibols in both their biomasses and exudates. The production of guttation droplets by indoor fungi may serve as a mechanism of aerosol formation for non-volatile metabolites in indoor air. A new computed motility inhibition (CMI) assay was developed to improve the screening of microbial contaminants. The CMI assay calculates objective toxicity values from digital micrographic videos of toxin-exposed boar spermatozoa experiments using a simple MATLAB® script. The results of the CMI assay were similar to the other established motility inhibition assays (BSMI and VMI assays). In addition, only the CMI assay was able to detect subtle changes in motility. The CMI assay was highly sensitive to the inhibition of mitochondrial function, glucose transport activity and the disruption of cellular cation homeostasis by ionophoric toxins. A new detection method for the airborne diffusion and toxicity of surfactants using two-compartment Petri dishes was developed. Genapol X-080, used in cleaning products, was selected as a model for polyethylene glycol monoalkyl ether surfactants. The airborne diffusion of Genapol X-080 was observed and evaluated as a change in the surface tension of water and the fluorescence of resazurin. The boar spermatozoa toxicity assays were the most sensitive to airborne Genapol X-080 than the inhibition of cell proliferation assays. The resazurin + Genapol X-080 test showed potential for developing a new and easy method to track the airborne diffusion of PEG monoalkyl ethers used in buildings.
A doctoral dissertation completed for the degree of Doctor of Science (Technology) to be defended, with the permission of the Aalto University School of Engineering,, on 10 September 2020 at 12.
Supervising professor
Salonen, Heidi, Prof., Aalto University, Department of Civil Engineering, Finland
Thesis advisor
Mikkola, Raimo, Dr., Aalto University, Finland
Kurnitski, Jarek, Prof., Tallinn University of Technology, Estonia
IAQ, PVC, airborne emission, mycotoxin, genapol, guttation droplet, toxicity
Other note
  • [Publication 1]: Castagnoli, E; Backlund, P; Talvitie, O; Tuomi, T; Valtanen, A; Mikkola, R; Hovi, H; Leino, K; Kurnitski, J; Salonen, H. 2019. Emissions of DEHP‐free PVC flooring. Indoor Air, volume 29, pages 903-912.
    Full text in Acris/Aaltodoc:
    DOI: 10.1111/ina.12591 View at publisher
  • [Publication 2]: Castagnoli, E.; Marik, T; Mikkola, R; Kredics, L; Andersson, M.A.; Salonen, H; Kurnitski, J. 2018. Indoor Trichoderma strains emitting peptaibols in guttation droplets. Journal of applied microbiology, volume 125, pages 1408-1422.
    Full text in Acris/Aaltodoc:
    DOI: 10.1111/jam.13920 View at publisher
  • [Publication 3]: Castagnoli, E; Salo, J; Toivonen, M.S; Marik, T; Mikkola, R; Kredics, L; Vicente-Carrillo, A; Nagy, S; Andersson, M.T; Andersson, M.A; Kurnitski, J; Salonen, H. 2018. An evaluation of boar spermatozoa as a biosensor for the detection of sublethal and lethal toxicity. Toxins, volume 10, article number 463.
    Full text in Acris/Aaltodoc:
    DOI: 10.3390/toxins10110463 View at publisher
  • [Publication 4]: Castagnoli, E; Andersson, M.A; Mikkola, R; Kurnitski, J; Salonen, H. 2018. Airborne toxicity of a non-ionic alcohol ethoxylate surfactant and wetting agent used in cleaning chemicals. Indoor Air 2018, Philadelphia, USA, 22 to 27th July 2018. ISIAQ. Paper ID:413