| Abstract: | The hygienic properties of two types of processing oils used in the manufacture of galvanised metal air ducts mere investigated. One of the oils was based on mineral oil and the other on vegetable oil. Evaporation of the oil emulsions from the galvanized metal surface was followed for ten months, after which the water-binding capacity of the residues was measured in increasing and decreasing RH at the range of 75-100%. The potential of processing oil residues to act as nutrients for fungi was tested with Penicillium brevi-compactum in the laboratory. The odour emission of oil residues was evaluated with the aid of a trained panel for eight months. After the ten months, the residue of mineral-oil- and vegetable-oil-based products was 60% and 79% of the original amount, respectively. Both oils were able to absorb water but desorption of the water from vegetable-oil-based products was delayed, thus increasing the risk of fungal growth. The residues of both oils provided sufficient nutrients for fungal growth. The odour emissions from the oil residues were high and that of vegetable oil tended also to increase. To attain high indoor air quality, duct manufacturing methods which do not leave residues should be developed. |
