Determination of emission factors for nitrogen oxides and volatile organic compounds emitted from jewelry making workshops

Introduction: Air pollution is a major problem in Isfahan, one of the major cities of Iran. A large number of jewelry making workshops are located in Isfahan, yet there is insufficient information about their pollutants emission rates. The aim of this study is to determine the emission factors of nitrogen oxides and volatile organic compounds (VOCs) in Isfahan’s jewelry making workshops. Materials and methods: In the first step of this study, some jewelry making workshops were visited to find nitrogen oxides and VOCs emission sources. It was revealed that the only possible source of nitrogen oxides and VOCs in these workshops was use of the oxy fuel welding system used to melt gold. In the second step, a set of experiments was conducted to determine the emission factors of nitrogen oxides and VOCs while working with the oxy fuel welding system. Results: The results of this study showed that the emission factor of nitrogen oxides in the oxy fuel welding system was 0.64 kg/kg consumed natural gas. It was also found that no VOCs were emitted while working with the oxy fuel welding system, since sufficient pure oxygen was produced in this system. Interview with managers of some jewelry making workshops showed that the average natural gas consumption in each workshop was 22 kg. Therefore, each jewelry making workshop in Isfahan emitted nearly 14.08 kg of nitrogen oxide per month. Conclusion: It is revealed that in 2018, 81100.8 kg nitrogen oxides were emitted from jewelry making workshops into Isfahan’s atmosphere.