Repeated daily exposure to 2 ppm nitrogen dioxide upregulates the expression of IL-5, IL-10, IL-13, and ICAM-1 in the bronchial epithelium of healthy human airways. - Pathmanathan, S.; Krishna, M. T.; Blomberg, A.; Helleday, R.; Kelly, F. J.; Sandstrom, T.; Holgate, S. T.; Wilson, S. J.; Frew, A. J.; Sandström, T (Occupational & Environmental Medicine, 2003)