Spatial distribution, diffusion characteristics and associated exposure risks of typical pathogenic aerosol emissions...

Informal landfill mining is an important emission source of pathogenic aerosols. In this study, the spatial distribution characteristics and diffusion behaviors of typical pathogenic bacterial aerosols (including Escherichia coli, Staphylococcus aureus and Salmonella) during mining in informal landfills were systematically investigated. The results revealed that the aerosol concentrations of the three pathogens in the mechanical operation area were greater than those in other areas. The mean aerosol concentrations followed the order of E. coli > S. aureus > Salmonella, with the majority of pathogenic aerosols detected within the particle size range of 2.1 ∼ 3.3 µm. Diffusion behavior analysis revealed that under low wind speed conditions, the aerosols tended to accumulate near the excavation source. As wind speed increased, although plume concentrations were diluted, the impact range extended several kilometers downwind. Moreover, the presence of multiple release sources collectively significantly elevated the peak aerosols concentrations and broaden the pollution scope. Quantitative microbial risk assessment results showed that the infection probability and disease burden for all three pathogens exceeded regulatory benchmarks without personal protective equipment (PPE). For Salmonella and S. aureus under high- and moderate-risk scenarios, exposure concentration remained a dominant risk factor, while the protective effect of PPE was relatively limited. Therefore, stricter management measures and engineering controls were needed to mitigate exposure to highly pathogenic bacteria during landfill mining process. This study contributes to a deeper understanding of the distribution, diffusion and health risks associated with pathogenic aerosols generated during refuse mining in informal landfills.