“Forever Chemicals” Are Escaping From Landfills — And We Need to Pay Attention to Both Ways Out
PFAS chemicals, the toxic “forever” compounds that make food boxes grease-proof, carpets stain-resistant, and jackets shed rain, don’t magically disappear once we toss them in the trash. They end up in landfills where, instead of breaking down, they slowly work their way back into our environment…and into the water we drink and the air we breathe.
And here’s the key thing a growing body of research tells us: PFAS doesn’t stay put. It leaves landfills in two major ways — through water and through air — and both pathways need real solutions in order to keep people safe.
And the reason this matters is simple: PFAS are harmful to people. Once they enter our bodies, they stick around for years and can interfere with the immune system, thyroid function, and healthy development. PFAS exposure has been linked to higher cholesterol, pregnancy complications, and certain cancers. These chemicals even cross the placenta and show up in breast milk, meaning exposure can begin before birth. And to understand why these two pathways exist, we have to understand what PFAS actually is.
PFAS isn’t one chemical — it’s a whole family with different behaviors
One reason PFAS moves through landfills in different ways is because PFAS isn’t a single chemical — it’s a massive family of thousands of compounds. Some PFAS dissolve in water. Others evaporate into air. Some cling to plastics and clothing. Others break off coatings and enter soil. This chemical diversity is the reason PFAS leaves landfills through two pathways:
Water-loving PFAS (like PFOA and PFOS) leave through leachate.
PFOA and PFOS are well-known “legacy” PFAS once used in everything from nonstick coatings to stain-proof carpet. They’re especially good at dissolving in water, which means they readily wash out of buried waste and into landfill leachate. These compounds dissolve easily in liquid. When rainwater filters through buried trash, it picks up these PFAS and forms leachate — the contaminated wastewater that landfills send to treatment plants.
Air-loving PFAS (especially fluorotelomer alcohols, or FTOHs) leave through landfill gas.
FTOHs behave almost like fumes. They evaporate, attach to landfill gas, and drift off-site unless they’re captured early and burned at high temperatures. FTOHs also transform inside the human body into other toxic PFAS that stay in the blood for years.
These phase differences, whether a PFAS prefers water or air, explain why landfills have two distinct PFAS pathways. And they’re exactly why we need strong, targeted solutions for both.
PFAS in water: the leachate loophole
Most people’s first encounter with PFAS in landfills is leachate — the dark nasty liquid that drains out of landfills when rain percolates through buried waste and mixes with the moisture released as organic material breaks down. As it moves, it picks up PFAS and delivers it straight to wastewater treatment plants that, in most cases, simply can’t remove these chemicals. Those PFAS don’t degrade in treatment; they move straight into rivers, lakes, and drinking water supplies.
Groups like those behind LeachateLoophole.org, led by New York River Watch and joined by partners like Sound Rivers in North Carolina, helped shine a spotlight on this disturbing problem. Their investigations found PFAS levels in leachate that were far beyond what downstream communities should face, and show how wastewater plants unintentionally become conduits sending PFAS back into the environment.
Solutions are challenging, but potential fixes include requiring landfills to pretreat leachate where levels are high so that it does not leave the landfill until it is safe, ensuring wastewater plants have the technology to filter and destroy PFAS, and monitoring downstream waterways so people know what they’re drinking. Communities shouldn’t have to guess what’s coming out of their taps.
But leachate is only half the story.
PFAS in air: the overlooked escape route
The second way PFAS escapes landfills is through the air, carried by landfill gas. As waste decomposes, volatile PFAS — especially fluorotelomer alcohols (FTOHs) — evaporate from everyday products and hitch a ride with the gas produced inside the landfill. Unless that gas is collected, PFAS drifts beyond the landfill’s boundary.
FTOHs are a problem because they don’t just evaporate, they transform. Once inhaled, these volatile PFAS break down inside the body into other harmful PFAS that linger for years and are linked to immune suppression, thyroid disruption, developmental impacts, and certain cancers. In the environment, FTOHs travel easily through the air and degrade into persistent PFAS that contaminate soil and water far from their source. In other words, FTOHs act like a mobile delivery system for PFAS pollution, spreading it quickly and making it harder to clean up.
A nationwide study recently sampled landfill gas at 30 landfills across 17 states, finding PFAS levels in the tens of thousands of nanograms per cubic meter, with some sites far higher. Researchers estimated U.S. landfills release roughly 836 kilograms of PFAS into the air each year, and potentially much more depending on site conditions. Even spread over a year, that makes landfills one of the larger known sources of PFAS to the atmosphere, at concentrations in landfill gas that are hundreds to thousands of times higher than normal outdoor air.
This aligns with earlier work by Lin et al., who found that many neutral PFAS (that can be found in both liquid and gas form) actually prefer the gas phase, meaning they escape through landfill gas far more readily than they dissolve into leachate. In several cases, these volatile PFAS were released almost entirely through gas.
And here’s the uncomfortable part: we’re flying nearly blind. Only a handful of studies have ever measured PFAS in landfill gas. Almost no landfills test the air at their boundaries. Monitoring of PFAS in waterways downstream of landfills is spotty at best. For chemicals that bioaccumulate and can negatively affect the immune system, thyroid function, and long-term health — whether inhaled or ingested — that lack of basic information is a problem. It doesn’t have to stay this way.
The stakes are high and solutions are needed
On the water side, we need modern wastewater plants and consistent pretreatment. That means upgrading municipal treatment systems with technology capable of actually filtering and destroying PFAS, not just passing it downstream. It also means requiring landfills to treat leachate onsite — capturing PFAS at the source, where the waste stream is most concentrated and easiest to manage. States should align drinking-water standards, leachate monitoring, and wastewater permits so PFAS can’t slip through regulatory gaps. These updates won’t just reduce PFAS contamination — they’ll protect rivers, drinking-water intakes, and the communities that rely on them.
But on the air side — where PFAS escapes through landfill gas, the fixes are remarkably practical, and several states are already pointing the way.
Start collecting landfill gas much earlier.
PFAS starts off-gassing long before many landfills install gas systems. States like California and Michigan are ensuring earlier gas collection for methane — a policy that would dramatically reduce PFAS emissions too.Capture more of the gas that’s produced.
Better gas collection system design and operation— approaches used in states like Maryland and Oregon can significantly increase gas recovery and reduce emissions.Use enclosed, high-temperature flares.
PFAS doesn’t reliably break down in open or low-temperature flares. Enclosed flares operating at consistently high temperatures are the most effective tool we have today. States like Washington already lean heavily on enclosed flares for better air quality. PFAS makes the case for them even stronger.And we need real monitoring.
No landfill should be allowed to discharge PFAS into the air or water without measuring it. Right now, almost none do. EPA can change that by requiring PFAS monitoring for both landfill gas and leachate — and by setting standards based on what the science shows.
Some landfills, like Smiths Creek in Michigan, are already piecing together what a whole-system solution looks like: pairing PFAS treatment for leachate with strong gas controls and continuous, high-temperature operation. It’s proof that the approach works.
We need more data — and leadership from policymakers who hold the pen
PFAS is leaving landfills today and every day — through the water beneath them and the air above them. We have the tools to dramatically reduce those harmful emissions.
States or the EPA can lead that effort. And the sooner we start, the sooner we’ll protect the air we breathe and the water we drink.
