Wood processing work stations constitute an environment producing contaminants affecting air quality in plant production facilities. A significant role among these contaminants is played by spores and hyphae of microscopic fungi. Their presence in respirable and settled dust directly affects health of employees working in those facilities. Moreover, microscopic fungi also interact with the components of wood causing its degradation. In view of the above it was decided to test several elements affecting the quality of ambient air by analysing samples collected from all accessible locations in the plant, where wood waste is accumulated. The samples were tested in terms of their concentrations of ergosterol, total phenolics, antioxidant activity as well as contents of endogenous wood sterols such as desmosterol, cholesterol, lanosterol, stigmasterol and beta-sitosterol. Analyses showed that wood waste, despite the varied location and exposure time, is material promoting growth of microscopic fungi. Several significant correlations between the analysed parameters need to be stressed, which made it possible to design the sterol bioconverison mechanism for wood, taking place as a result of growth of microscopic fungi on the wood material.