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Burning garbage is a poor solution to the global garbage crisis

Updated: May 26

It's not ecologically friendly. It's not environmentally sustainable. I'll explain why in just a bit.


First let's talk about how much garbage is burned in the United States. Turns out it's more than a tenth. This is around 30 million tons of garbage going up in flames every year.


Do you have a hard time conceptualizing 30 million tons? OK, I do too! Let's do this:


A Nimitz-class aircraft carrier is about 100 thousand tons.

Imagine roasting 300 Nimitz-class aircraft carriers...in one year.


The United States has about 300 cities with populations of 100,000 or more.


What if each of those cities made, then melted, one Nimitz-class aircraft carrier, every year, at an annual warship service?


That's a lot of matter being created and then burned.

A Nimitz-class aircraft carrier, seen here transporting Starscream replicas.


Now that I've written "Nimitz" more times than in the rest of my life combined, let's talk about why burning garbage is bad.


Reason 1: Most modern garbage contains plastic


What happens when you burn plastic? Picture the smoke and ash from a campfire, and you have the right image. Except, make the ash plastic, not wood, and turn the smoke into a cloud of microplastics.


By now you've probably heard a lot about microplastics and how prevalent they are, even winding up on remote mountaintops via standard wind patterns, in Arctic snowfall, and even in our tap water. So, microplastics travel everywhere. But how are they made?


Making microplastics: Rubbing and burning


Most microplastics found in the environment are the result of fraying and rubbing of larger plastic surfaces. When your polyester clothing wears out, smaller bits of plastic fiber are being mechanically detached from the larger mesh of fibers. The same thing happens with plastic bags floating in water, or yogurt cups sitting in landfills. This kind of generic mechanical decomposition is pretty slow, on a timespan best measured in days to years, but it is still fast enough to have already covered Earth and its lifeforms in microplastics.


A much faster way to break apart plastic is to burn it. This is decomposition by combustion, which in the case of plastic is best measured in seconds to minutes. If most plastic were decomposed through combustion rather than mechanical degradation, we'd be generating microplastics much more quickly from the same amount of plastic, and spreading them across the world as plastic ash and plastic smoke.


What's wrong with plastic ash?


Wood ash disappears over time due to biodegradation. This is why Earth is not covered in wood ash from all the forest fires that have occurred since forests first appeared.


Plastic ash does not disappear, because it does not biodegrade. Biodegradation requires organisms to do the biodegrading, and the majority of plastic types are not biodegradable by any known organism. The few types of plastic that are biodegradable do so weakly, and only in controlled contexts. Bioengineers are trying to make better plastic biodegraders, but these efforts have a long way to go, and there's still the question of how to safely and effectively deploy them once we have made them.


What about plastic smoke?


Plastic smoke is made of the same stuff as plastic ash, but the particles are much smaller in size. The smallest ones, known as nanoplastics, are small enough to enter animal bloodstreams and even brain tissue. Breathing plastic smoke incurs the same respiratory problems as does breathing wood smoke, including lung irritation and increased risk of cancer. In addition, the chemical structures of plastics mean that plastic particles easily soak up carcinogenic, teratogenic, and even toxic chemicals that wood particles do not, and all of these chemicals can be transferred to tissues and cells in your body after you have breathed them in on floating, invisible particles of plastic.


Incinerators do not capture all the ash and smoke they create


This is intuitively obvious to anyone who has ever spent time near an industrial burn station of any kind. Air quality is poorer around these locations. And it's not just because of companies breaking the law to evade pollution standards, though this does happen all the time.


The more fundamental scientific problem is that we rely on filters to capture the particle output of fires, and these filters all have problems. Some filters only capture certain kinds of chemical, but let others through. Other filters work based on size, with smaller particles easily passing through. For instance, Singapore is famous for burning all of its garbage nationwide. Its garbage incinerators all have one-micron filters, which sounds impressive until you learn that all nanoplastics are smaller than one micron, and plastic fires unavoidably generate nanoplastics. This means that Singapore is spewing nanoplastics into the atmosphere every time it runs its garbage incinerators. (Note that I'm not trying to pick on Singapore here. They are doing the best they can with an impossible trash situation that they were forced into by other countries, including the United States.)


Finally, all types of filter eventually break down and must be replaced. This is expensive to do on a large scale. Thus, filters tend to be swapped as infrequently as the incinerating company can get away with doing, as befits their profit motive.


The bottom line is that no filter exists that can capture arbitrarily small particles forever, which makes all garbage incinerators a source of airborne nanoplastics pollution.


Let's talk about size


The term "microplastics" covers a large range of sizes, from the millimeter scale down to the nanometer scale. This is six orders of magnitude. This is the same length ratio that exists between a millimeter and a kilometer. If you shrink a kilometer down to a millimeter, then something that was previously a millimeter is now a nanometer.


Let's visualize this with our favorite expository tool, the Nimitz-class aircraft carrier. If you line up three of these metal war ducks in a row, you have taken up a kilometer of linear space.

Three separate Nimitz-class aircraft carriers lined up perfectly from prow to stern.


Shrink all three carriers to the thickness of the last fingernail fragment you clipped off.


Congratulations! With the power of the human imagination, you have performed a length reduction of six orders of magnitude!


Now picture your fingernail clippers, lying there forlornly on the deck of a Nimitz, because that's where you like to groom and, bless you, you're a butterfingers who just can't hold onto the dang things.


Well when the boat shrank, the fingernail clippers shrank by the same proportion.


In the shrunken reference frame, aircraft carriers are a microplastic and fingernail clippers are a nanoplastic.


Perhaps now it is a little clearer why even filters designed to capture microplastics might not capture nanoplastics, and why nanoplastics can potentially go places, like brains and blood cells, where even microplastics cannot.


Does it matter where nanoplastics go?


We previously mentioned that plastics are great transporters for certain carcinogenic, teratogenic, and toxic chemicals. The more these chemicals can work their way into the most sensitive machinery of the body, including brain tissue and the interiors of cells, the more likely they are to cause problems in humans. As the smallest class of plastic, nanoplastics are likely to have the easiest access to these sensitive biological sites, where they can drag in and deposit harmful chemicals soaked up by the plastic beforehand. Judging by reports of plastic-driven disease in coral reefs and the long-term development of human immune responses to other supposedly "immune-silent" synthetic polymers, plastics may also serve as fouling agents, allergic triggers, and immune depressants in their own right.


This is especially important when you think about how plastics and other persistent chemicals bioaccumulate up the food chain. Bioaccumulation is the process of many smaller organisms being eaten by progressively fewer and fewer larger organisms, forcing the chemicals in them to be progressively concentrated to higher and higher concentrations in the bodies of the larger organisms. This is perhaps most famously known in the context of bioaccumulating mercury through high tuna consumption, but it is true for any persistent chemical or particle, including plastic. Humans are already eating a lot of microplastic, and bioaccumulation only worsens things.


But plastics (including nanoplastics) carry more than harmful chemicals. They may also pick up and transport organisms, including pathogenic ones like bacteria and viruses. This property of being a pathogen vector may even be directly contributing to the ongoing extinction of coral reefs.


How does all this nanoplastic talk relate to burning garbage?


Mostly because they are so small, nanoplastics are hard to study. As such, very little is actually understood about them. Even the term "nanoplastic" itself is fairly new. That said, given what we know about the differences between mechanical and combustive modes of decomposition for other major classes of long-chain polymer (like those found in wood or insect shells), it is probably a good bet to view plastic incineration as a much more rapid generator of nanoplastics, and a much more efficient spreader of nanoplastics into the environment, than landfill disposal could ever be.


So we can solve all these plastic issues by dumping it in landfills?


No. Absolutely not! But incineration is not a good solution, either. In a future essay, I'll talk about real steps to fix the plastic crisis, and what "fixing" it would even mean.


This essay was supposed to be about all garbage, not just plastic


Right! There is another big reason that burning garbage is bad.


Reason 2: Modern garbage is extremely poisonous and becomes more poisonous when you burn it


Modern garbage doesn't only contain plastics. It also contains massive amounts of toxic, carcinogenic, and teratogenic compounds, which can soak into plastics but are also harmful all on their own. For a well-studied example of this, consider flame retardants, which exist in thousands of products and are terrible for living things.


And of course there are the more obviously harmful compounds that remain on product containers when you throw them away. Think of all the bleach, insectide, battery acid, ammonia, drain cleaner, oil, heavy metals (from arsenic to mercury to lead), and every other nasty thing you have ever thrown into a garbage can.


Now think of millions of other people throwing those same nasty things into their own garbage, all of that garbage being packed into 300 Nimitz-class aircraft carriers, and the entire garbage fleet set on fire like a Michael Bay rendition of the Battle of Blackwater Bay.


What happens when all those chemicals burn together?


If you've ever read about Mordor, or spent any time in the Wasatch Front, you have a rough approximation of what the air quality might permanently be like around these garbage fires.


(Obviously I'm kidding. Most of those chemicals probably didn't exist in the Third Age.)


But incineration plants are supposed to filter their output


This is true. And I refer you to the section above where I discussed the limits of incineration filters. Some incineration plants try their best to be environmentally responsible (and many do not), but even the best of technology has not kept pace with the best of intentions.


One thing to keep in mind about the harmful garbage chemicals I listed a few paragraphs back: Unlike plastic, they are not long-chain polymers. They are individual small molecules, with sizes well below one micron. This means that when they are evaporated, they will pass straight through size-selective one-micron filters like those used by Singapore's incineration plants.


We also briefly mentioned filtration by type of chemical or particle. The unfortunate truth about chemistry is that a method used to capture one type of molecule, like a metal, is unlikely to capture an unrelated molecular structure, like an organic ring. Different types of filtration systems can be stacked, but these multi-layered stacks can be difficult to maintain because of cost and complexity. In a society that treats waste disposal as a straightforward balancing act between maximizing profit and avoiding shutdown by underfunded regulators, this results in a big difference between what is theoretically possible (filtration that is wide-spectrum and efficient, but not universal or complete) and what tends to be actually observed (poor or no filtration).


These filtration issues are not easy problems to solve, and I have yet to hear about an incineration plant anywhere in the world that has solved them all. (That would be a chemistry miracle, actually.)


Garbage incineration is an inherently polluting activity


Burning garbage is not clean, it's not sustainable, it's not safe. It might be one among several bad options that, collectively and unfortunately, comprise the best we can do at this moment. However, we should not pretend that it is a long-term solution, or even a good short-term one.


We are spinning ever deeper into a global garbage crisis brought on by long-term, entrenched, heavily defended economic habits that are the pinnacle of an astonishingly short-sighted approach to living on our only livable planet. The fact that we think this crisis is solvable by setting fire to more things is perhaps as telling as it is ironic and sad.


We need to do a lot better, both as rational beings and as empathetic ones


One of my next essays discusses some ideas for how we can do better.


Thanks for reading!



Image of aircraft carrier from https://en.wikipedia.org/wiki/Nimitz-class_aircraft_carrier

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