Objectives Organic dust is associated with adverse effects on human airways. This study was done to investigate whether the addition of β-(1,3)-D glucan or aldehydes to office dust causes enhanced inflammation in human airways. Methods Thirty-six volunteers were exposed randomly to clean air, office dust, dust spiked with glucan, and dust spiked with aldehydes. The three dust exposures contained between 332 and 379 µg dust/m 3 . Spiking with 1 gram of dust was done with 10 milligrams of glucan or 0.1 microliters of aldehydes. Acoustic rhinometry, rhinostereometry, nasal lavage, and lung function tests were applied. Results After the exposures to dust spiked with the glucan and aldehydes, the nasal volume decreased (-1.33 and -1.39 cm 3 (mean), respectively) when compared with the -0.9 cm 3 after clean air or office dust (P=0.036 for a difference in decrease between exposures). After 2-3 hours the aldehyde-spiked dust caused a 0.6-mm swelling of the inferior turbinate, and glucan-spiked dust produced a 0.7-mm swelling (P=0.039 for a difference in the swelling between the four exposures). The preexposure nasal lavage cleaned off the mucosa, and lower cytokine concentrations were found after all of the exposures. For interleukin-8, this decrease in concentration was smaller after the dust exposures spiked with glucan and aldehydes (-2.9 and -25.8 pg/ml, respectively) than after office dust or clean air (-65.9 and -74.1 pg/ml, respectively) (P=0.042). The nasal eosinophil cell concentration increased after exposure to dust spiked with glucan (P=0.045). Conclusions β-(1,3)-D glucan and aldehydes in office dust enhance the inflammatory effects of dust on the upper airways.