Exposure EffectsSulphur dioxide is

Exposure Effects

Sulphur dioxide is irritating to the eyes, throat and respiratory tract. Short-term overexposure causes inflammation and irritation, resulting in burning of the eyes, coughing, difficulty in breathing and a feeling of chest tightness. Asthmatic individuals are especially sensitive to SO2 (Baxter, 2000) and may respond to concentrations as low as 0.2-0.5 ppm. Volcanologists suffering from asthma may notice adverse effects at concentrations substantially below those that affect their colleagues. Prolonged or repeated exposure to low concentrations (1-5 ppm) may be dangerous for persons with pre-existing heart and lung diseases. While health effects are documented at various concentrations by different researchers and organizations, a sampling of thresholds for health effects are outlined in the table.
Health effects of respiratory exposure to sulphur dioxide
(Baxter, 2000; Nemery, 2001; NIOSH 1981; Wellburn, 1994)
Exposure limits (ppm) Health Effects
1-5 Threshold for respiratory response in healthy individuals upon exercise or deep breathing
3-5 Gas is easily noticeable. Fall in lung function at rest and increased airway resistance
5 Increased airway resistance in healthy individuals
6 Immediate irritation of eyes, nose and throat
10 Worsening irritation of eyes, nose and throat
10-15 Threshold of toxicity for prolonged exposure
20+ Paralysis or death occurs after extended exposure
150 Maximum concentration that can be withstood for a few minutes by healthy individuals

High levels of ambient SO2 have been shown to cause various health problems in children (Ware et al., 1986). However, studies at Mt Sakurajima did not show a correlation between prevalence of asthma in children and prolonged exposure to volcanic gases (Uda et al., 1999).