Characterization and health risk assessment of particulate and gaseous pollutant emissions from polystyrene injection molding

Polystyrene (PS) is widely used in society and the environment, which has significantly contributed to the dramatic growth of its industry. Laboratory studies have indicated that the injection molding process of PS can generate harmful. However, there is limited information available on the airborne contaminants generated during the actual injection molding process of PS. To illustrate the health risks of workers exposed to aerosols generated during the actual injection molding process of PS, the particulate and gaseous pollutants were analyzed in a real environment. Temporal variations in particle concentrations and size distributions were monitored using a real-time measurement system, while gaseous pollutants were collected and analyzed through gas chromatography-mass spectrometry. Health risks were assessed following the Environmental Protection Agency guidelines. The results indicated that the PS injection molding process generates a high concentration of particles, particularly nanoparticles. The PM 2.5 mass concentration exceeded the World Health Organization guideline limits, although the total particle concentration remained below the Occupational Safety and Health Administration exposure limits. The detected gaseous pollutants, including methylene chloride, toluene, ethylbenzene, o-xylene, and styrene, were present at low concentrations (< 12 × 10 –3 ppm). The individual hazard quotients and overall hazard index were less than 1, indicating a low non-carcinogenic toxic risk. However, lifetime cancer risk assessments for styrene and ethylbenzene suggest potential carcinogenic risks for workers with exposure durations exceeding 10 years. These findings highlight the necessity for implementing strategies to mitigate particulate and gaseous pollutant emissions, thereby reducing potential health risks. This study enhances our understanding of the pollutants during the actual injection molding process of PS and provides valuable insights into the associated health risks for workers.