Microplastics have been found everywhere from oceans to the air we breathe, and now, researchers have discovered that green roofs may help stop them in their tracks.
A groundbreaking study from Tongji University in Shanghai has revealed that green roofs – already known for their many environmental benefits – may also play a surprising role in capturing microplastics from rainfall.
The Findings:
- Green roofs were shown to trap up to 97.5% of microplastics carried by rain.
- The substrate (growing medium) was the most effective part of the system for filtration, outperforming plant surfaces and roots.
- Even partial coverage can make a big difference. Shanghai’s 3.56 million m² of green roofs may already capture over 56 metric tons of microplastics annually.
Why It Matters:
Microplastics are a growing concern worldwide, found in oceans, rivers, the air we breathe, and even our food. This study suggests that expanding green roof coverage in cities could provide a powerful new tool to help tackle this invisible pollutant.
Added Benefits:
Alongside this newly identified role, green roofs are already well-recognised for:
- Reducing flood risk through stormwater management
- Improving energy efficiency in buildings
- Enhancing urban biodiversity
- Supporting climate resilience
Points of Caution:
Researchers noted that fibre-shaped microplastics may become airborne again under windy conditions, and that plastic-based components within roof systems could contribute to new microplastic generation over time.
Looking Ahead:
As with any new discovery, this study opens up as many questions as it answers. For instance:
- What happens to the microplastics once they are captured by the substrate?
- Could long-term build-up affect the plants or the performance of the roof?
- How might maintenance practices adapt to remove or manage the particles effectively?
While the study did not attempt to answer these questions – understandable, given how recent this finding is – what it does provide is an exciting new starting point for research and innovation.
This is just the beginning of the conversation, and further studies will be needed to understand the long-term implications. For now, this discovery adds yet another reason to view green roofs as a vital part of sustainable urban design.
If you’re interested in exploring the study in detail, including methodology and data, the full research paper can be accessed here.