In 2017, China banned the import of "foreign garbage," a category that includes 24 types of recyclable and solid waste.
China used to be the world's top importer of plastic waste. According to a 2018 report, China imported more than 1 million tons of plastic waste from 1992 to 2016 — around 45% of the global total.
Other countries in Southeast Asia, including Thailand and Malaysia, have started buying up some of the recycling exports that had previously gone to China.
Recycling facilities across Southeast Asia have tried to take in some of the world's recycling exports, but they could not match China's volume, according to National Geographic.
With China's ban now in place, some cities in Malaysia are overrun with the world's plastic waste.
The 2018 study estimated that 111 million metric tons (122 million tons) of plastic waste will be displaced by 2030 because of China's new policy.
Much of this garbage has already made its way to China's maritime neighbor, Malaysia, which imported more than 754,000 metric tons (830,000 tons) of plastic waste from January to June of 2018, according to Greenpeace.
Recognizing that there was money to be made from Malaysia's burgeoning plastic industry, locals in Jenjarom established illegal recycling factories throughout town.
Many plastic recycling plants in Malaysia are unmarked and rented from local landlords.
Jenjarom is located about 15 miles southeast of Malaysia's main port, Port Klang. The town's proximity to Port Klang made it a prime dumping ground for items that entered through the port.
Instead of handing over un-recyclable scraps and parts to waste centers, the illegal factories cut costs by burning those scraps, releasing noxious fumes.
Burning plastic can release toxic chemicals like mercury, dioxins, and polychlorinated biphenyls (PCBs) into the atmosphere, which poses a threat to human health.
A 2016 study found that burning plastic waste could increase the risk of heart disease and cause damage to the nervous system. The study also noted side effects like rashes, headaches, nausea, and worsened asthma.
The link between burning plastic waste and cancer is more tenuous, since it depends on how long a person is exposed. Over a long period of time, plastic fumes could become carcinogenic.
Local residents have said they started to become ill around the same time that the garbage piles arrived.
Residents in Jenjarom told the BBC they experienced rashes and violent coughing attacks.
A single site near a palm oil plantation in Jenjarom contains 4,400 tons of waste.
Malaysia's environment minister told the BBC that no one was interested in purchasing the contaminated site when the state government tried to auction it off.
She added that transporting the garbage to a cement plant could cost nearly 2.5 million Malaysian ringgits ($615,000 USD).
The piles of trash are a problem throughout this region of Malaysia. In October, a worker in Pulau Indah told Reuters there were at least eight illegal factories in the island district.
In July, the nation's housing authority investigated 114 permitted factories and found that only eight met their requirements.
The housing authority suspended all 114 factories' permits for three months and asked them to re-apply under stricter criteria.
Though the waste has yet to disappear, the government is hesistant to ban plastic imports, given the lucrative nature of the business.
