HYGIENIC ASPECTS OF PROCESSING OIL RESIDUES IN VENTILATION DUCTS

The hygienic properties of two types of processing oils used in the ma nufacture of galvanised metal air ducts were investigated. One of the oils was based on mineral oil and the other on vegetable oil. Evaporat ion of the oil emulsions om 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 fung i was tested with Penicillium brevi-compactum in the laboratory. The o dour emission of oil residues was evaluated with the aid of a trained panel for eight months. After the ten months, the residue of mineral-o il- and vegetable-oil-based products was 60% and 79% of the original a mount, respectively. Both oils were able to absorb water but desorptio n of the water from vegetable-oil-based products was delayed, thus inc reasing the risk of fungal growth. The residues of both oils provided sufficient nutrients for fungal growth. The odour emissions from the o il residues were high and that of vegetable oil tended also to increas e. To attain high indoor air quality, duct manufacturing methods which do not leave residues should be developed.