Laboratory and field comparison of three methods for monitoring sulfur dioxide in air

The purpose of this test was to establish the relative response of Du Pont Pro-Tek C-20 SO2 air monitoring badges with NIOSH Physical and Chemical Analytical Methods (P&CAM S308 and 160) in field tests at a steel mill blast furnace area during normal slag release operations. No significant difference was found at the 95% confidence level between the badges and P&CAM S308. The correlation coefficient between the badges and P&CAM S308 was 0.996. The NIOSH P&CAM 160 gave considerably lower results in the field. Exposures ranged from 6.3 to 35.4 ppm airborne sulfur dioxide. Analysis of field-exposed badges stored for five days at room temperature showed no loss of absorbed SO2 when compared with badges analyzed immediately. Prior to field testing, badges and impingers were validated in the laboratory using certified gas cylinders containing SO2 in air over the anticipated exposure range. Both impinger methods, when validated in the laboratory, met NIOSH accuracy requirements for a sampling and analytical method.