Scrubbing Earth of per- and polyfluoroalkyl substances—a.k.a. PFAS or forever chemicals—could eliminate a list of woes for people and planet. Used for decades in everything from nonstick pans to firefighting foams, PFAS have been linked to increased risks of fertility challenges, developmental delays, cancer, and reduced immune response. They are known for a strong bond between carbon and fluorine, which the environment struggles to break down. 

The sticking points

PFAS are everywhere: They spew from factories and slough off products and into water with normal use. Scientists have found them in everything from human blood to Antarctic snow. One 2022 report found that 89% of the US population had PFAS in excess of two nanograms per milliliter of blood plasma, a common threshold for potential adverse health effects, and 9% of the population had passed the riskier level of 20 nanograms per milliliter.

The PFAS monster is also a moving target. New compounds are still being created and used. There are more than 12,000 of them, and much of the cleanup research focuses on only a small handful. 

The progress

Cleansing PFAS-contaminated soil is a project in its infancy, but it is possible to prevent more buildup by pulling the chemicals out of water systems. There are two ways to handle this: trap or destroy. Some scientists have found reverse osmosis—a process that pushes water through supertight filters—useful in point-of-use cases, like water filters at kitchen sinks. 

Other techniques in the pipeline might be more suitable for large-scale removal—for example, at water treatment facilities. One, called foam fractionation, generates bubbles that capture PFAS. More approaches, like ensnaring the chemicals in nanothin layers of charged metal, are also under investigation. 

Trapping, though, is imperfect. You’re left with PFAS-filled brine, which if not properly destroyed (an expensive and energy-sucking endeavor) can still end up in the environment. 

Jack Huang, a professor of crop and soil sciences at the University of Georgia, is working on destruction. He’s testing a method called electrochemical degradation, which uses electrodes to break down the bonds that hold PFAS together. The product destroyed more than 90% of PFAS mass in tests and has already been licensed by the engineering consulting firm AECOM. 

Ridding life of PFAS is also a policy challenge. There are alternatives; we just need the push to use them. And we’ve had success before: The EPA’s 2010/2015 PFOA Stewardship Program has helped slash the release of water-repellent perfluorooctanoic acid by 95%. More recently, Minnesota, Maine, and New Mexico have passed bans on PFAS in products like cookware and dental floss. 

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Progress meter ………… 6

Scientists are making strides toward removing and destroying PFAS—but it’ll be all for naught if we don’t turn off the tap. 

Every year, traffic crashes kill more than one million people, and they’re the leading cause of death for children and young adults. In the US, 100 people a day lose their lives this way, in many cases not on highways but on rural and local streets. “Traffic deaths are a leading cause of preventable death, yet we treat it like it’s inevitable,” says Leah Shahum, founder and director of the Vision Zero Network, a nonprofit focused on making streets less deadly. 

The sticking points

The causes of a crash can be muddy. Drivers make mistakes like speeding or getting distracted, but infrastructure fails them too: Perhaps they were on a road built for speed and not safety, in a screen-filled vehicle, or at an intersection where pedestrians, cyclists, and other cars aren’t visible. 

Cheap and proven traffic-calming opportunities abound—from using planters to tighten intersections to lowering speed limits—but government logjams and red tape can be speed bumps. “There’s so many moving parts,” says Laura Sandt of the University of North Carolina Highway Safety Research Center. “On the flip side, it shows that we have so many opportunities for injury prevention.” 

The progress

The total number of traffic deaths has increased over the last century. And though the US rate has dipped from a peak of 30.8 deaths per 100,000 people in the 1930s, the past decade has seen a concerning jump in deadly pedestrian incidents. At the same time, communities are waking up to the essential role of traffic safety policy, Shahum says. 

One success story is Hoboken, New Jersey, which hasn’t had a traffic fatality since 2017. This is due to a combination of efforts like boosting investment in public transit, promoting walkability by extending curbs, and using cameras to identify crash-prone intersections in need of a redesign. But even there, obstacles remain. If an intersection hasn’t been proved to be deadly, for example, it can be an uphill battle to argue for removing parking spaces to widen curbs. “You’re kind of selling insurance through these improvements, and that’s not always easy,” says Greg Francese, the city’s acting director of transportation and parking.

There’s also no silver bullet that will work everywhere. Situated directly across the river from New York City, Hoboken is a highly transit-oriented city of less than 60,000 people. Success there might not translate to traffic-death hot spots like Memphis or Dallas. But it’s not impossible. Take Edmonton, Alberta, a sprawling, car-centric Canadian city of around one million people: Between 2015 and 2020, it cut traffic fatalities by 63% and serious injuries by 40% by adjusting speed limits and improving signals at crosswalks. 

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Progress meter ………… 6

We know how to tweak intersections and adjust traffic signals. Getting the funding and will to roll out those changes is the big red light.