Lead particulate generated from ruby heat treatment in Chanthaburi province

Abstract

Lead glass heating has been long used in the gem industry in Thailand. Recently, it has become a concern to environmental scientists and the gemologist communities because of its dangers to health and the environment. Hence, determination was made of lead concentration in respirable particulate from the process of ruby heat treatment involving lead glass. Two home factories in Chanthaburi Province were selected for the sampling sites. Three parts of sample collections including 1) emission profile of lead from the ruby treatment furnace, 2) exposure of the treater to lead in the home factory and 3) lead concentration in indoor air of the home factory. The results show that lead particulate can emit from the furnace only during gate opening period and the highest concentrations were found within the first 10 min after gate opening. In addition, lead particulate emitted from furnace increases as amount of lead additive or ruby increases. Regarding determination of lead exposure to the treater and residents, the results clearly indicate that both mixing step and opening period of furnace are the main periods of lead exposure. Moreover, higher amounts of lead additive added into the process appear to emit higher amounts of lead. For indoor lead concentration, ruby heat treatment using lead glass clearly elevates the lead concentration within the home factory and providing an efficient ventilation system and separating the treatment area from living area can reduce the effect of lead from the process.