In July, a fire broke out at the Jatiwaringin landfill and continued to burn for 10 days. The fire was unusual for its size and duration, but this type of pollution is common in Indonesia: people burn trash every day.
"We are breathing microplastics," said Mohammad Reza Cordoba, a senior scientist at Indonesia's National Research and Innovation Agency in Jakarta.
The impact could be severe and spread beyond the country's borders.
Hundreds of people in the surrounding area were treated for acute respiratory infections after firefighters brought the blaze at the dump under control, authorities said. The trash pile included tens of thousands of tons of plastic, which shattered into tiny pieces as the fires raged.
Microplastics are generally defined as fragments less than five millimeters in length, slightly smaller than the diameter of a plastic straw. The smallest nanoplastics are less than one micron in size and are most likely to enter human blood and tissue.
Researchers have also found tiny fragments of plastic - plastic is not biodegradable and breaks down into smaller and smaller pieces - in human brains, breast milk and amniotic fluid.
According to a study published by Cornell University in 2024, Indonesia leads the world in microplastic intake. Researchers found that the average Indonesian consumes 15 grams of plastic particles per month, which is equivalent to the weight of three credit cards. The country also has some of the highest concentrations of microplastics in the air globally. Researchers have found plastic debris in the air in 18 cities in the country, with Jakarta having the highest concentrations.
This pollution is the toxic legacy of the country’s longstanding plastic waste management woes. Reza and colleagues report that the amount of microplastics on the ground increases fivefold after it rains—suggesting that concentrations of these substances in the air are already very high.
Washing synthetic clothing also releases microplastics into sewage, which can enter rivers and oceans. Certain types of car tires also produce microplastics as they wear.
All of this has global implications because Indonesia is located between two oceans. The United Nations says the country is the world's second-biggest plastic polluter after China. Indonesia has a developed fishery and exports more than 1 million tons of seafood to Asia and North America every year. Researchers have found microplastics in manta rays, milkfish and snapper caught in Indonesian waters.
Moreover, once the trash itself enters the ocean, it can travel great distances.
Scientific research into how microplastics affect the human body is still in its early stages. But a 2024 study published in the New England Journal of Medicine found that patients who underwent surgery to remove blockages in their carotid arteries and whose plaques were removed from the arteries were found to have microplastics were 4.5 times more likely to have a heart attack, stroke or die within the next 33 months than those whose plaques contained no plastic.
Controlled experimental studies show that exposure to tiny plastics can trigger inflammation and cell damage.
“I have no doubt that microplastics are a cause of disease and a cause of premature death,” said Dr. Philip Landrigan, director of the Global Health Program at Boston College. “No reasonable person could possibly assume that microplastics in the human body are harmless.”
But it may be years before the public gets a clearer picture. Scientists say a fundamental problem in understanding how microplastics affect human health is that they cannot reliably measure the tiniest particles that can enter human cells. While several studies have shown a link between microplastic exposure and disease, they do not prove that microplastics cause these diseases.
Kevin Thomas, an environmental health scientist at the University of Queensland, said the challenge for researchers now is figuring out what levels are potentially harmful.
However, he added: "Limiting contact is solid advice."
Last year, Indonesian Health Minister Budi Gunadi Sadikin held a press conference to warn that people should wear masks if it rained in Jakarta. The announcement, prompted by Reza's findings, led to a flood of warnings about "plastic rain" in Indonesian media. But Reza said the public should also be worried about the dry season, when people may inhale microplastics suspended in the air.
Following the minister's warning, Jakarta resident Wasiu Lilik became more insistent on wearing a mask while commuting, a habit he developed during the coronavirus pandemic.
"I used to be more worried about air pollution in Jakarta, but since the issue of microplastics has been widely discussed, it has heightened my concerns," said Wasiu, who works in marketing.
Burn garbage
One of the main reasons airborne microplastic pollution is so high in Indonesia is the open burning of garbage, according to Indonesian researchers.
According to a 2023 survey by the Indonesian Ministry of Health, about 57% of Indonesian households burn garbage, although it is illegal; the global average is 14%.
Millions of people have to burn their trash because there are few garbage collection services outside cities. Recycling is not widespread. Many low-income people can only buy shampoo, coffee and detergent in cheap plastic packets, which are piling up in mountains of garbage across the country.
These dumps present a fire hazard. In July, officials said they were preemptively spraying water on Jakarta's Bantargbang dumpsite during the dry season because of high concentrations of flammable methane gas that accumulated in the pile. The dump is taller than the Statue of Liberty and covers an area larger than 200 football fields.
Last year, non-profit organization Ekoton said it had found microplastics in the air in 18 Indonesian cities.
In June, Indonesian Environment Minister Mohammad Jumhur Hidayat set a deadline of 2027 for all local governments to completely stop open dumping of garbage. But environmentalists say that deadline is highly unlikely to be met.
Microplastics in water
When Reza collected rainwater from the roof of his laboratory in north Jakarta in 2022, he expected to find those familiar tiny bits of plastic, known as microplastics.
But he was struck by how numerous they were, and how dominant one type of microplastic was: synthetic fibers.
His findings echo those of a study by the International Union for Conservation of Nature, a global environmental network. The study concluded that washing clothes in washing machines is one of the world's largest sources of household microplastic pollution.
During the wash cycle, the friction of your washing machine can cause tiny plastic fibers to break off. Research shows that faster spin speeds and hot water make these fibers shed more easily. Washing clothes by hand or using lower spin speeds produces less microplastic emissions.
In countries with advanced sewage treatment systems, most of these tiny fibers are trapped by integrated filtration facilities. But in Indonesia, there are few such facilities. Laundry wastewater often drains into drains or streams, causing millions of fibers to flow directly into rivers.
When these rivers dry up in the sun, the fibers stay in place. Over time, they are picked up by the wind and accumulate in the atmosphere. When it rains, it washes away dust, pollutants and microplastics suspended in the air.
Ecoton researchers sampled 68 rivers in Indonesia and found that synthetic fibers accounted for nearly half of all microplastic pollution in these waters.
