The relationships between indoor environment factors and signs of eye irritation were studied in a sample of female personnel with (n = 112) and without (n = 64) mucous membrane symptoms working in 36 nursing departments at geriatric hospitals in the municipality of Trondheim, Norway. The indoor climate was characterised by high room temperature (interquartile range 23.0-23.7 degrees C), low relative air humidity (interquartile range 17-26%) and high outdoor airflow rate, as indicated by low indoor levels of carbon dioxide (interquartile range 490-650 ppm). An altered microbial flora was observed in nine of the departments, and Aspergillus fumigatus was found in three of these. Five of the hospitals were situated in urban parts of the municipality near roads with heavy traffic. In the initial analyses decreased tear-film stability (BUT) was observed in subjects working in departments with increased dust settlement rate (P = 0.03), in hospitals situated in urban areas with heavy traffic (P < 0.001), and in subjects working in departments with presence of A. fumigatus (P = 0.04). Increased conjunctival staining (CS) was related to alteration of the microbial flora. In the final multivariate analyses statistically significant relationships were observed between BUT and dust settlement rate and urban vicinity of workplace and between CS and alteration of the microbial flora.