Sensory and pulmonary effects of acute exposure to sulfur dioxide (SO 2)

Abstract

Background Exposure to sulfur dioxide (SO 2) affects large populations worldwide. Pulmonary effects have been reported at concentrations relevant in the general (<0.5 ppm) and working environment (>0.5 ppm). SO 2 is an irritant but the existing studies often emphasize only pulmonary effects and no clear dose–response relationship has yet been described. Objectives Using a multi-level, multi-method approach, odor annoyance, sensory irritation and pulmonary effects of SO 2 were to be investigated in an experimental exposure study. Methods Eye 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. Results Eye blink frequency, nasal airflow, and lung function were not affected by the acute SO 2 exposure investigated. These physiological responses to moderate SO 2 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. Conclusions In healthy volunteers, without hyperresponsiveness to SO 2, no dose-dependent effects of acute SO 2 exposures up to 2 ppm could be measured. Due to olfactory perceptions subjects were aware of the different SO 2 exposures but the associated annoyance was relatively low.