CAW National Council 4000
Occupational Health and Safety

Hazardous Substances:  Sulphur Dioxide

Sulphur dioxide can create ill-health effect if it is inhaled or if it comes in contact with the eyes or skin.

Short-Term Effects

Sulphur dioxide is a pungent, suffocating, irritating, colourless gas. It is readily soluble in water forming sulphurous acid. This may
occur when the gas contacts moist skin, the mucous lining of the respiratory tract and the eyes. It is intensely irritating to the eyes
and respiratory tract causing burning of the eyes and tearing, coughing, and chest difficulties. With low to moderate exposure.
Exposure to higher concentrations can cause death either by suffocation due to laryngeal spasm and edema or due to severe
chemical pneumonitis. It may cause severe breathing difficulties. Severe exposure to sulphur dioxide may cause a person to stop

If the person perspires dermatitis may result. A single extreme exposure to the gas can produce permanent pulmonary fibrosis
(scarring) of the lung.

Long-Term Effects

Occupations exposure is generally to repeated low concentrations of sulphur dioxide. Over many years it may affect the teeth in the
same way as sulphuric acid does. Long-term effects on the lungs include bronchitis and emphysema where sulphur dioxide is at
least a contributing cause. The lung damage when it occurs is permanent.


Enclose process
Local exhaust ventilation
General dilution ventilation
Personal protective equipment


ACGIH TLV 2ppm (5.2 mg/m3).
U.S. NIOSH recommendation 0.5 ppm.

Source:  CAW Health, Safety & Environment Department