Landfills release toxic ‘chemicals’ into the air

The disparity between liquid and landfill gas is significant because compared to systems that collect seepage or seepage, systems that collect gas “are not nearly as efficient,” says environmental engineer Ashley Lin of the University of Florida in Gainesville. What’s more, the portion of the gas that’s captured on-site isn’t typically treated in ways intended to destroy PFAS, she says. “The real concern is how we manage this really concentrated gas that we’re putting out.”

PFAS molecules contain elastic bonds of carbon and fluorine atoms, which contribute to their resistance to heat, grease and water, as well as their widespread use in consumer products such as raincoats, cosmetics and non-stick cookware. But these bonds also cause PFAS to linger in the environment, with some forms taking more than 1,000 years to degrade.

Surprisingly, researchers have found that these chemicals permanently accumulate within most, if not all, US landfills and their effluents. For example, a 2023 EPA report showed that effluent from more than 95 percent of 200 landfills across the country contained PFAS, identifying 63 different types of PFAS across sites. But few studies have investigated what types and amounts of PFAS are escaping into landfill gas.

For the new study, Lin and her colleagues sampled and analyzed gas from three municipal solid waste sites. Of the 27 types of PFAS they tested for, 13 were detected, with combined concentrations ranging from 210 to 940 parts per trillion. A single class of PFAS that typically exists in the gas state, called fluorotelomer alcohols, dominated the PFAS in the samples, reaching concentrations that were somewhat comparable to those in fumes from soil near a PFAS production facility, the researchers note.

The team also took leachate samples from each landfill. But since those samples harbored different types of PFAS than the gas, the researchers compared how much of a common PFAS building block — fluorine — the leachate and gas samples contained. They found that comparable amounts of fluoride from PFAS were being released from the waste into runoff and gas, and in one location roughly three times as much leaked into the gas.

A landfill’s location, time of year and different detection methods can affect the amount of PFAS found in gas and leachate samples, says environmental chemist Florentino De la Cruz, who was not involved in the study. More data will be needed to complete the nationwide picture, and a national sampling campaign funded by the US Environmental Protection Agency is underway, says De la Cruz, of the University of North Florida in Jacksonville.

But it’s clear that landfill gas carries chemicals forever, he adds. “This is no longer controversial.”

Lin says questions also remain about the fate of the emitted PFASs. Landfill-captured gas is often burned in flares like flares, but it remains unknown whether this process destroys PFAS.

As for PFAS-laden gas escaping from a landfill, “you have an air release that gets diluted very, very quickly,” says civil and environmental engineer Morton Barlaz. “I think the levels are so low that it’s unlikely to cause one [health] influence.” However, he says, it is still too early to say for sure.

Research shows that household products can also release PFAS that are concentrated within indoor dust, says Barlaz, of North Carolina State University in Raleigh. “If I think about a house a half mile, a mile from a landfill, I’m more concerned about the dust and if they have old carpet and old couches that have been treated with PFAS,” he says. “My God, this is in their house.”