Scientists are developing a framework to measure plastic emissions

Researchers at the University of Toronto have developed a framework for measuring plastic pollution emissions – similar to the global standard for measuring greenhouse gas emissions.

They say the approach will boost the identification of the biggest contributors to plastic pollution from local to national levels and improve strategies for reducing emissions globally.

Using Toronto as a model, the first framework of its kind suggests that Canada’s largest city emitted nearly 4,000 tonnes of plastic pollution in one year alone.

“That’s about 400 garbage truckloads of plastic leaking into the environment every year from across the city,” says Alice (Xia) Zhulead author of a study describing the method published in Environmental sciences and technology.

“Attributing responsibility for pollution to a jurisdiction with the ability to legislate means that there is no hiding where the pollution comes from. It provides an opportunity to identify the main sources of plastic pollution in the area and take action to curb these emissions.”

A PhD student in the Department of Natural and Environmental Sciences at U of T Scarborough who works together with a university lecturer Chelsea Rocheman at U of T’s Department of Ecology and Evolutionary Biology in the Faculty of Arts and Sciences, Zhu developed the framework with colleagues from U of T and the Rochester Institute of Technology. The researchers were inspired by guidelines for drawing up greenhouse gas emissions inventories, drawn up by the United Nations Intergovernmental Panel on Climate Change. Adjusting for physical differences between greenhouse gases and solid pieces of plastic, the researchers used a similar methodology to identify the main pollution-generating activities in a given area, calculating the amount of pollution generated by each activity within a given period and took into account the uncertainties involved. with any source of polluting activities.

The framework comes ahead of international discussions in Ottawa, April 23 to 29, on a legally binding global agreement on plastic pollution. The discussions are led by the UN Intergovernmental Negotiating Committee on Plastic Pollution.

“Our goal was to develop an accounting mechanism or tool for measuring plastic emissions that any level of government can adopt,” said Zhu. “But most importantly, we hope that this tool we have introduced will enable the plastics field to follow in the footsteps of the climate field, where countries submit national emissions inventories to an international body like the United Nations to monitor our progress in the towards achieving a global goal. defined purpose.”

Currently, no national emissions inventories of plastic pollution exist, nor is there a globally defined target for reducing plastic pollution.

To demonstrate the usefulness of the framework, the researchers created a plastic pollution emissions inventory for the City of Toronto for the year 2020, based on publicly available data collected through municipal litter audits and other sources. From a list of nine types of sources – including litter, tire dust from aircraft and road vehicles, washing machines and paint from road markings and the exterior of houses – they estimate that between 3,531 and 3,852 tonnes of plastic pollution was emitted from the EU. city ​​limits during that period.

Litter made up the largest share of the total at 3,099 tonnes, while artificial grass was responsible for the most emissions of microplastics – particles smaller than five millimeters in diameter – at 237 tonnes.

“Unsurprisingly, larger materials – known as macroplastics, and in this case from poorly managed waste such as litter – make up the majority of the mass. But it overshadows the little things: microplastics,” says Rochman, co-author of the study and Zhu’s supervisor. “Microplastics are usually the highest in terms of number of pieces. This suggests that policies relevant to microplastics, in addition to macroplastics, are critical to reducing plastic emissions in the City of Toronto.”

The researchers chose Toronto to test the framework as it is the largest city in Canada and the fourth largest in North America.

“It’s an urban hub for different activities – and where there are a lot of people and activities, you inevitably create a lot of pollution,” says Zhu. “For a successful and informative case study, you want to look at a place with many different sources of pollution. By doing this you can identify which sources should be prioritized for pollution reduction, thereby demonstrating the usefulness of an emissions inventory in informing local policy.”

Zhu said plastic pollution emissions inventories should be a fundamental part of a successful global treaty on plastics, and that the framework should be applied to other cities, provinces and states, and countries around the world to better understand what types of plastic pollution exist take place. released into the environment.

“The guidelines can be applied to regions around the world, regardless of what types of resources exist,” Zhu said. “Each geographic region will have different characteristics and the inventory will enable the development of solutions tailored to that specific region.”