A new study has overturned assumptions about airborne plastic pollution, finding that a rural woodland area recorded higher levels of microplastic deposition than a nearby city.
The research, undertaken by a team from the University of Leeds and Oxford, sampled air fallout along a rural-to-urban gradient in southeast England from May to July 2023.
Surprisingly, the highest average deposition rate – reaching as high as 500 particles m² per day – was found in Wytham Woods, a rural nature reserve.
Oxford City, despite its dense population and traffic, showed lower overall deposition but the greatest diversity of polymer types.
The smallest microplastics, measuring 25 – 50 micrometres, dominated across all sites, accounting for up to 99% of particles during high-deposition events.
The most common plastic types also varied by location: PET (common in bottles and packaging) was abundant in the rural woodland; polyethylene (used in bags and packaging) dominated the suburban site; and EVOH (linked to industrial and automotive uses) was most prevalent in the urban centre.
The study found that weather was a key driver. Higher wind speeds significantly increased deposition, while increased atmospheric pressure suppressed it. Rainfall washed microplastics from the air, reducing overall fallout but increasing the proportion of slightly larger particles.
The research was led by Dr Gbotemi Adediran, Lecturer in Earth Surface Geochemistry in the University of Leeds’ School of Earth and Environment. He said: ‘Our research reveals that rural environments are not necessarily safe from airborne microplastics – and highlights how natural features like trees influence pollution patterns.
‘This shows that microplastic deposition is shaped not just by human activity, but also by environmental factors, which has important implications for monitoring, managing, and reducing microplastic pollution.
‘The widespread presence of smaller microplastics raises concerns about potential health risks from inhalation, regardless of whether people live in a city or a rural village.’
The findings challenge the assumption that urban areas invariably experience the worst microplastic air pollution. The authors suggest the high rural deposition may be due to the ‘comb-out effect,’ where trees capture airborne particles and to long-distance transport of microplastics by wind.
Dr Adediran said: ‘Our findings highlight the impact of weather patterns on microplastic dispersion and deposition, and the role of trees and other vegetation in intercepting and depositing airborne particles from the atmosphere.
‘The study highlights the need for further research into long-term deposition patterns of microplastics, focusing on specific plastic types and sizes, and their relationship with short-term and seasonal weather variations across diverse landscapes.’
The full research can be read here.
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