Microbial levels and diversity in bioaerosols from electronic waste dismantling facilities

Bioaerosols emitted from electronic waste dismantling facilities pose a potential occupational and environmental health hazard due to their complex composition and associated pathogenic risks. However, comprehensive assessments of their microbial dynamics and inhalation exposure risks remain limited. This study systematically investigated the concentrations, size distributions, community structures, and exposure levels of bacterial and fungal aerosols across different functional areas of an e-waste recycling plant in Shanghai over winter and spring seasons. Results revealed that the dismantling and crushing workshops were primary sources of bioaerosols, with significantly elevated concentrations in spring. Size distribution analysis showed a predominant enrichment of microbial particles in the respirable size fractions ( 2.1-0.65 μm). Microbial community analysis identified Firmicutes and Bacillus as the dominant bacterial phylum and genus, while Ascomycota, Aspergillus and Penicillium prevailed among fungi. Notably, several enriched species, including Aspergillus flavus and Penicillium citrinum, are known potential mycotoxin producers, highlighting a direct health threat. Seasonal variation accounted for only a small proportion of the variation in microbial community structure; however, the exposure assessment indicated higher average daily dose (ADD) and hazard quotient (HQ) in spring, particularly in high-activity workshops. Although all HQ values were below the risk threshold (HQ = 1), the elevated exposure levels in key areas during spring underscore the necessity for enhanced engineering controls and personal protective equipment, especially for male workers facing relatively higher risks.