Bioaerosols in the atmospheric environment of oil exploitation sites: spatial and temporal distribution, sources, influencing factors, health risks, and reduction efficiency of masks.

Particle-bound microorganisms have attracted increasing attention due to their health effects and pollutant metabolic activity. However, the characteristics of airborne microbes in oil exploitation sites with heavy particulate matter and volatile organic chemicals (VOCs) pollution remain unclear. This study collected bioaerosol samples in a city polluted by oil exploitation in the Beijing-Tianjin-Hebei region of China, and investigated the spatial and temporal distributions, sources, influencing factors, health risks, and filtration efficiency of bioaerosols. The results showed that the average culturable and total bioaerosol levels in autumn were significantly higher than in summer, whereas microbial activity exhibited an inverse seasonal trend. Higher concentrations were found in steel plants, inland oilwell, and chemical industry park, suggesting that industrial activities may increase bioaerosol levels. No significant correlation was observed between microbial activity and concentration. The microbial communities' diversity and abundance varied significantly between seasons, with crude oil degradation bacteria, Anoxybacillus and Curtobacterium as dominant bacteria, Cladosporium and Alternaria as dominant fungi. SourceTracker analysis showed that airborne bacteria were primarily derived from leaf surface, while the contribution of leaf surface and soil communities to atmospheric fungi is more prominent. Airborne bacteria were more influenced by VOCs, while environmental factors have greater impact on fungal community structures. The hazard quotient (<1) of inhaling bioaerosols was negligible, but long-term exposure to dominant pathogens, Bacillus and Mycobacterium, could be harmful. Actual wearing masks could only remove 13.7% of bioaerosols, far lower than laboratory-measured values. In summary, this study elucidates the influence of oil exploitation activities on shaping the airborne microbial community, offering practical insights for risk assessments and control of bioaerosols in oil exploitation sites.