Microorganisms involved in composting can become airborne during turning-over and screening, potentially impacting the health of workers and nearby residents. This study investigated bioaerosol emissions at a municipal solid waste composting facility and their associated health risks. Air samples were collected at multiple locations, from 100 m upwind of the facility to 100 m downwind of the facility boundary, to assess bacterial and fungal concentrations. The highest bioaerosol levels with a mean concentration of 9307 CFU/m3 and 763 CFU/m3 for bacteria and fungi, respectively, were observed at the turning-over site, followed by the screening area. Bioaerosol concentrations declined with distance from the turning-over site, and at 250 m downwind, bioaerosol levels fell below background concentrations, indicating a safe zone for surrounding communities. Environmental factors such as wind speed influenced bacterial emission from composting piles, while temperature is negatively correlated with fungal concentrations in ambient air, likely due to low humidity in the semi-arid climate. The findings indicate that certain composting stages release elevated bioaerosol levels, particularly bacteria, posing potential health risks to workers. However, exposure risks for nearby residents appear minimal, and fungal bioaerosols pose a low risk due to reduced spore survival under low-humidity conditions of semi-arid regions.
Mirzaienia et al. (2026) studied this question.