Abstract The aim of this study was to examine microbial, chemical and physical (particle) emissions from organic and inorganic thermal insulations with a multifunctional apparatus developed for this purpose. In addition, basic quality parameters of the insulation materials, including microbial content, ignition residue and density, were determined. The particular focus of the study was on bast fibrous insulations made of bast fibres of flax, linseed and hemp. The amounts of microbes in the dry insulations varied greatly, up to 10 7 cfu / g . Several taxa of fungi were detected from the bast fibrous insulations, some of which may produce toxins in suitable conditions. The lowest microbial contents were found in the commercial products. However, emissions of moulds from all insulations made from bast fibres were significant at 90% RH, whereas at lower RHs they were negligible. Only a minor amount of emissions was detected from the reference materials at any RH. Emissions of bacteria were negligible for all materials and conditions. The emission levels of VOCs were negligible for all materials except recycled wood. However, several components of the VOC emissions were identified. No significant emissions of particles were detected from thermal insulations made of bast fibres of flax and hemp. In the case of insulations, particularly those made of organic fibres, it is essential to follow good manufacturing practices and to keep the insulations in a dry place throughout the manufacturing and building process in order to minimize hygienic risks in insulations.