90 Measurements of benzene exposure in the oil and gas industry – comparison between passive and active sampling

Exposure to benzene is still an occupational hazard in the oil and gas industry. The Norwegian occupational exposure limit (OEL) for benzene has recently been reduced to 0.2 ppm – which, according to the Norwegian legislation gives an OEL of 0.12 ppm for 12h shifts used in the oil and gas industry. Thus, raising the need to more up to date exposure assessment and also to measure exposure on tasks which previously might have been overlooked due to presumed low exposure. Air sampling of benzene was performed with TD tubes (Carbopac X) both with passive sampling and active sampling (20 mL/min). For the passive sampling the TD-tubes were equipped with a diffusive cap and for the active sampling TD-tubes with a diffusion lock was used to prevent contamination. In total 426 workers, both at offshore facilities and land-based facilities within the oil and gas industry participated in the study. Resulting in 390 active and 425 passive samples of benzene with a total of 385 measurements where both active and passive sampling were performed on the same worker. There was no statistically significant difference in measured air concentrations of benzene offshore compared to onshore. A slightly higher benzene concentration was measured using passive air sampling compared to active air sampling, however, no statistically significant difference between active and passive air sampling was found.