Sensory and pulmonary effects of acute exposure to sulfur dioxide (SO2)

BackgroundExposure to sulfur dioxide (SO2) affects large populations worldwide. Pulmonary effects have been reported at concentrations relevant in the general (<0.5 ppm) and working environment (>0.5 ppm). SO2 is an irritant but the existing studies often emphasize only pulmonary effects and no clear dose–response relationship has yet been described.ObjectivesUsing a multi-level, multi-method approach, odor annoyance, sensory irritation and pulmonary effects of SO2 were to be investigated in an experimental exposure study.MethodsEye blink frequency, rhinomanometry, spirometry and symptom ratings of acute health effects were assessed before, during, and after the exposures. Each session lasted 4 h and concentrations of 0.5, 1, and 2 ppm were investigated and compared to a control condition using clean air. Sixteen human volunteers (8 females/8 males) participated and during exposure light physical exercise was simulated with bicycle ergometry.ResultsEye blink frequency, nasal airflow, and lung function were not affected by the acute SO2 exposure investigated. These physiological responses to moderate SO2 exposures were not significantly affected by gender. Regarding subjectively measured chemosensory sensations, only odor annoyance ratings increased in a dose-dependent manner, but the average magnitudes were labeled weak to moderate.ConclusionsIn healthy volunteers, without hyperresponsiveness to SO2, no dose-dependent effects of acute SO2 exposures up to 2 ppm could be measured. Due to olfactory perceptions subjects were aware of the different SO2 exposures but the associated annoyance was relatively low.