Fire insulations of ventilation equipment and shafts as a source of man-made mineral fibres

The sources of man-made mineral fibres (MMMFs) settled on furniture surfaces and in supply air were determined in an office building. The impact of renovation on indoor air and the perception of air quality by the occupants were studied. Renovation improved the air-tightness of the inner parts of structures. Settled MMMFs were collected with gelatine tape by pressure and deposition techniques. MMMFs in supply air were collected using the filter installed to the supply diffuser. Sources of MMMFs were determined by comparing the found fibres to the fibres of insulation materials in the building using SEM/EDS. Occupants perceptions of air quality and how it affected their wellbeing were collected using a questionnaire. The results showed that MMMFs originated mainly from fire insulations outside the main air ducts in shaft structures. The renovation improved indoor air quality and reduced the number complaints and symptoms of occupants. This study indicates that it is important to maintain the air-tightness of building preventing air leakage from shaft structures to indoor air.