When China banned plastic waste imports in 2018, countries like the United States, the Netherlands, Australia, and Japan didn't stop exporting plastic waste — they diverted their shipments to countries in Southeast Asia.
New research led by Ellen Considine, fellow at the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder, shows that air pollution in Indonesia worsened in 2018 and 2019, when the country began receiving some of the plastic waste that previously went to China. Municipal waste collection is limited in Indonesia and open burning of solid waste is common.
The work, published in the Journal of the Royal Statistical Society - Series C: Applied Statistics, highlights a recurring environmental justice issue: wealthy nations exporting pollution and its consequences to lower-income countries with less capacity to refuse or manage it.
"When high-income countries ship plastic waste to low- and middle-income countries, more plastic waste tends to be burned," said Considine, who is also an assistant professor of Geography at CU Boulder. "This releases air pollutants that can cause respiratory disease, cancer, or even death to local residents."
Considine and her co-author, Rachel Nethery from the Harvard T.H. Chan School of Public Health, leveraged satellite data to evaluate changes in fine particulate matter at 356 open dump sites in Indonesia before and after China's ban on plastic waste imports. Fine particulate matter is the air pollutant of greatest concern for human health because it consists of particles small enough to penetrate human lungs and enter the bloodstream.
"Previous studies of the impact of plastic waste burning on air quality have been more localized, for instance by deploying an air quality monitor in a couple of locations for a few months," Considine said. "Our approach is powerful because it allows us to look at air pollution changes over a large study region and time period and identify a connection to plastic waste imports."
The team used advanced statistical methods to determine how much of the increase in air pollution was due to China's policy change and waste burning versus other factors that vary over time, like weather.
The results suggest the policy change and waste burning caused an average 3.3 percent increase in fine particulate matter at open waste dump sites in Indonesia in 2018 and 2019 compared to 2012 to 2017. The potential health impacts are significant; the increase in fine particulate matter corresponds with an approximate 1.9 percent increase in mortality risk from lung cancer and a 3.5 percent increase in mortality risk from lower respiratory infections.
"Methods like this, for evaluating the impact of policies, have historically been developed by economists but have more recently been adapted by public health and environmental scientists," Considine said.
The analysis reveals a potential chain reaction after China's ban: some of the plastic waste that used to end up in China was diverted to Indonesia, leading to more open dumping and burning of plastic waste, which generated more fine particulate matter air pollution.
Considine and Nethery's work supports recent decisions by Indonesia and Malaysia, another country impacted by China's policy change, to ban plastic waste imports. The team's approach can be used to evaluate the effectiveness of these and future policies related to plastic waste and open burning.
"I am inspired by stories of air pollution research being used to inform policy decisions, " Considine said. "Efforts like ours help fill critical evidence gaps in places and for applications with more limited data."
