Figure 4From: Analysis of airway secretions in a model of sulfur dioxide induced chronic obstructive pulmonary disease (COPD)Secretory basal activity after 25 days of exposure to 5, 10, 20, 40 ppm SO2 or fresh air and 20 days exposure to 80 ppm SO2. Results are presented as mean ± SD cpm. ** indicates p < 0.01.Back to article page