A filter method for the active and passive monitoring of sulfur dioxide in workplace air

A method where sulfur dioxide is collected on impregnated filters (glycerol/potassium hydroxide solution) is described. Sampling can be done either with a pump or by the use of two different passive monitors available on the market. Analysis is made by ion chromatography. The methods have been evaluated and compared with a colorimetric air monitoring badge system (ProTek). Laboratory tests show that the accuracy of the filter methods is acceptable and that samples can be stored. Water vapor does not interfere, but hydrogen sulfide causes a minor decrease in recovery. ProTek has high accuracy but storage tends to decrease the recovery. Field tests in a steel rolling mill and a sulfate pulp mill showed a fairly good correspondence between the methods.