Toxic Dioxins Released in Air Risk Human Health and Reduce Crop Yields 

Of the most polluted cities in the world, few stand so prominently as Delhi, India. In fact, the Indian capital — which is home to more than 7 million people — has gained notoriety as the “air pollution capital” of the world. Until recently, scientists have been puzzled as to why Delhi sees thicker smog than other cities with widespread pollution issues, like Beijing. But a new study published in Nature Geoscience has uncovered what is likely the x-factor: burning plastic waste. 

Publishing their work in late January, researchers analyzed the particulate matter in Delhi and Chennai — large cities which both reside in the Indo Gangetic Plain, a region that is particularly prone to dense smog. Among their data, the team were most interested to find abnormally high levels of chloride. 

Chloride particles are foundational to the formation of water droplets. They are most ubiquitous along coastlines, where sea spray releases them into the air. The thick smog that has been blanketing Delhi and Chennai for decades is a representation of what happens when chloride levels reach extreme highs — highs which are now scientifically linked to the burning of plastic waste. 

While analyzing pollutants that increased concurrently with the chloride particles, researchers found that the chemical footprint matched the burning of household waste containing plastics, as well as the burning of plastics themselves. 

The fact is, with India’s massive population and stark socio-economic disparities, its developing infrastructure cannot effectively manage much of the waste that is produced. Because of that, according to the study authors, “Delhi experiences open burning of 216,000 Mg (over 476,000,000 pounds) of municipal solid waste (MSW) per year, some of which occurs at non-designated places and also ends up as fuel for brick kilns. This waste mainly constitutes diverse rubbish, but a common and abundant component is mixed plastic from food wrappers and e-waste.”

Burning plastic waste at a dumpsite in Mojokerto, Indonesia. Photo: Fully Handoko/EPA

The consequences of this process are already salient across India. In 2017 alone, particulate matter caused 12,000 excess deaths in New Delhi, write the study authors. Moreover, research has shown that when plastic is burned, toxic dioxins are released that increase ground-level ozone — a phenomenon which is estimated to reduce crop yields by 20 to 30 percent across the nation. 

As if the situation in India itself wasn’t dire enough, recent research suggests it carries significant implications on a global scale. 

Studies from chemists in Colorado and France have shown that beyond airborne pollution, plastic particles also circulate the globe to poison even the most remote areas. Notably, the Toulouse-based EcoLab research institute found alarming levels of microplastic in the Pyrenees.

The team, led by researcher Steve Allen, collected samples from high-altitude areas of the Pyrenee mountain range, far from any source of plastic pollution — “the nearest village was 6km away, the nearest town 25km, and the nearest city 120km.” Upon investigation, Allen found that “an average of 365 plastic particles, fibres and films were deposited per square metre every day.” 

“It’s astounding and worrying that so many particles were found,” says Allen. What’s especially troubling is that the remoteness of the region did not seem to spare it in any way. 

Referencing similar studies conducted in Paris, France, and Dongguan, China, the results of the Pyrenee study showcased “comparable” levels of microplastic. “And those are megacities where a lot of pollution is expected,” says Deonie Allen, a companion researcher at EcoLab. “Because we were on the top of a remote mountain, and there is no close source, there is the potential for microplastic to be anywhere and everywhere.”

Given that about 90% of waste in low-income countries ends up in open dumps or is burned in the open air, this discovery raises important questions regarding the spread of plastic throughout our environment, and its effect on life in all forms.

“We used to be surprised to find plastic pollution in a given location,” says Charlie Rolsky, Director of Science for Plastic Oceans International. “Now it’s shocking to find a clean ecosystem. What’s worse is that this is clearly just the tip of the iceberg. Sure, we’re finding this stuff everywhere, but what are the environmental implications? How many of those implications influence humans as well? Clearly, as well as urgent mitigation, further steps must be taken to better understand the impact of these plastics and what their roles are as environmental pollutants.”

Thankfully, according to the lead author of the chloride study and IIT Madras Department of Civil Engineering associate professor Sachin S. Gunthe, there is cause for optimism. “Given that we find plastic burning as a potential cause of the reduced visibility, we hope [our] findings will help policy makers to efficiently enforce and implement policies that are already in place towards regulating open burning of plastic contained-waste and other potential chlorine sources.”

Responsibility falls on all of us — the governments who fail to regulate, the corporations who spew plastic, and the consumers who welcome it so indifferently — to imagine the world we want to inhabit, reject its lesser versions, and make it so.

Isaiah Maynard is a US-based writer who covers environmental topics for a variety of publications and is part of the Environmental Journalism team at Ninth Wave.