Assessment of low dose effects of acute sulphur dioxide exposure on the airways using non-invasive methods

Sulphur dioxide (SO(2)) is an important environmental and workplace air pollutant. Some studies demonstrate that subjects without adaptation respond to SO(2) up to 10 ppm with irritative effects on the airways. The aim of our study was to assess irritative effects of SO(2) up to 2 ppm on the airways using non-invasive methods like exhaled breath condensate (EBC), nasal lavage fluid (NALF) and exhaled nitric oxide (FeNO). Sixteen healthy volunteers were exposed for 4 h to SO(2) in concentrations of 0 (clean air), 0.5, 1.0 and 2.0 ppm in a repeated measures cross-over design. Before and after exposure, FeNO and biomarkers of airway inflammation in NALF and EBC were measured. All EBC pH values, collected after exposure, were more alkaline than before, significant only for clean air (7.05 + or - 0.4 vs. 7.27 + or - 0.3, P = 0.0031) and 0.5 ppm SO(2) exposure (6.85 + or - 0.53 vs. 7.08 + or - 0.42, P = 0.0251). No dose-dependent differences before and after exposure were measured for LTB(4), PGE(2) and 8-isoPGF(2alpha). Substance P in NALF collected after exposure tended to result in higher concentrations compared to pre-samples, without clear dose effect. Further cellular and soluble parameters measured were not significantly affected. Our results show that 4 h SO(2) exposure up to 2.0 ppm did not induce significant changes in the biomarker composition of the EBC and NALF when compared with clean air or with pre-samples of the same subject. Therefore our data suggest that acute low dose SO(2) exposure in not adapted subjects did not induce airway irritation or/and inflammation measured under these conditions.