Evaluation of thermal desorption as an alternative technique for the measurement of coal tar pitch volatiles
Van der Merwe, Cornelius Johannes
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Motivation: The accurate and reliable measurement of the concentration of coal tar pitch volatiles (CTPVs) in ambient air has proved to be a challenge for occupational hygienists. The challenge must however be confronted due to, amongst others, the carcinogenic properties of some poly–aromatic hydrocarbons (PAHs) contained in CTPVs. Aim: To determine the feasibility of a thermal desorption (TD) technique based method as an alternative method to be used for the measurement of the concentration of CTPVs in ambient air by assessing it along criteria such as ease of use, cost, accuracy and precision by comparing it to NIOSH’s Method 5515 and OSHA’s Method 58 and to determine the level of exposure to CTPVs on the anode paste floor of an electric furnace, used for the smelting of platinum group metals (PGMs) concentrate. Methodology: To satisfy the research objective, two accepted methods the National Institute of Occupational Safety and Health’s (NIOSH) method 5515 and the Occupational Safety and Health Administration’s (OSHA) method 58 were used for the measurement of the concentration of CTPVs with a TD technique based method used as a third, alternative method. All three methods were used concurrently to measure the concentration of CTPVs in ambient air, at the anode paste floor of a platinum group metals (PGMs) concentrate smelter. Results and conclusions: The NIOSH method proved to be the most precise method while the TD technique based method proved to be the most accurate. The TD technique based method proved to measure the widest range of individual CTPVs and were able to measure the highest concentration of Benzo(a)pyrene, an individual CTPV that is classified as a Group 1 (carcinogenic to humans) chemical substance by the International Agency for Research on Cancer (IARC). The OSHA method measured on average almost four times less total CTPVs than either the NIOSH or the TD technique based method and failed to readily measure individual CTPVs with a molecular weight lower than that of Phenanthrene.
- Health Sciences