Atmospheric microplastic emissions from organic waste composting: Field-based assessment and exposure implications

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Pollution Control

Background:

• Organic compost is a significant source of environmental microplastics (MPs).
• Atmospheric microplastic pollution from composting is not well understood.
• Composting activities can disperse microplastics into the atmosphere.

Purpose of the Study:

• To investigate airborne microplastic pollution from different composting techniques.
• To compare microplastic emissions across reactor, stack, film-covered, and trough composting.
• To quantitatively assess human exposure risks from airborne microplastics during composting.

Main Methods:

• Employed active and dry deposition sampling for airborne MPs.
• Compared four composting techniques: reactor, stack, film-covered, and trough.
• Assessed human exposure risks via oral intake and inhalation pathways.

Main Results:

• Stack composting showed the highest MPs abundance (16.90 items m⁻³ active; 93.4 items m⁻² d⁻¹ deposition).
• Film-covered composting exhibited the lowest emissions (3.48 items m⁻³ active; 37.4 items m⁻² d⁻¹ deposition).
• Airborne MPs increased during composting, with smaller MPs (<800 μm) rising and average size decreasing.
• Human exposure risk peaked during stack composting and was minimal during film-covered composting.

Conclusions:

• Composting is a major pathway for atmospheric microplastic dispersion.
• Film-covered composting effectively mitigates airborne MPs and reduces human exposure.
• Optimizing composting practices is crucial for minimizing environmental microplastic contamination.