America Is Backsliding Toward Its Most Polluted Era

Updated at 11:37 a.m. on April 9, 2025

When you inhale a microscopic speck of soot, its journey may go like this: The particle enters your nose and heads into your lungs, penetrating even the tiny air sacs that facilitate gas exchange. Next it may slip into your bloodstream and flow into your heart, or past the blood-brain barrier. Most of us inhale some of these tiny particles every day. But inhaling enough can turn the act of breathing into an existential hazard, prompting or worsening asthma, COPD, respiratory infections, and permanent lung damage. In the heart, the specks can trigger heart disease, heart attacks, and most of the cardiovascular disorders you can think of. Air pollution is also associated with depression and anxiety, and with higher rates of suicide. It can trigger strokes and is linked to dementia or—even at average levels in this country—Parkinson’s disease.

These particles can also cross the placenta, where they can reduce an infant’s lung function before birth. A pre-polluted baby is also more likely to arrive prematurely, and at a lower weight. Exposure to bad air in utero is associated with a higher risk of autism, and exposure in childhood has been linked to behavioral and cognitive problems, including lower IQ. A person’s lungs can develop until age 25, and as Alison Lee, a pulmonologist at the Icahn School of Medicine at Mount Sinai, put it to me, “once you’ve lost lung function, you can’t get it back.” Persistent exposure to air pollution can cause permanent harm, creating health problems for children and setting them up to become sicker adults.

It’s hard to picture a person dropping dead from air pollution, yet it happens all the time. In the United States, particulate matter is estimated to kill more than twice as many people as vehicular accidents do—in total, some 100,000 to 200,000 people a year, as an underlying factor of chronic disease or by way of heart attacks, asthma attacks, and other sudden events. Even as air quality in America has improved, researchers have found that relatively low concentrations of particulate matter can cause major hazards.

All of this stems from a toxic and mostly invisible danger, largely the product of burning things for fuel and letting the remnant drift into the air and then into us—which is what happens unless the government regulates that process. The Trump administration, however, has shown little interest in doing so. Through new policies and aggressive cuts, the administration is taking steps that will encourage more pollution while muffling the science that shows the harms. The very air that Americans breathe will likely become less safe.

So far, the EPA has announced that it will pursue a suite of rollbacks of environmental rules, among them a Joe Biden–era update to standards for particulate matter that were meant to be fully in force by 2032 and that the Biden EPA projected would, in that year alone, prevent up to 4,500 premature deaths and 800,000 cases of asthma, reaping up to $46 billion in health benefits. It also plans to reassess a rule limiting the amount of airborne mercury and arsenic that power plants can release. In a statement announcing one of these rollbacks, the EPA said that the U.S. has already made major gains in air quality, implying that these are enough. In response to a request for comment, an agency spokesperson told me that EPA Administrator Lee Zeldin’s priority is “clean air, land, and water for EVERY American.”

The air in the U.S. certainly is cleaner than it was when industrial air pollution billowed into the skies unmitigated. Over the past 25 years alone, particulate air pollution in the country has dropped by more than 30 percent. Yet at least one in three Americans lives in a place where the air is still a health hazard. The particulate-matter standard that Zeldin intends to roll back is still nearly twice as high as the limit the World Health Organization recommends to protect health.

Rolling back rules will take time, but America’s air quality could worsen in the interim. The EPA told businesses last month that they can simply email the agency if they want an exemption from certain pollution regulations and that “the president will make a decision.” However they address those pleas, this opens a back door. The recent cuts to EPA personnel almost certainly mean that enforcement will suffer too. Meanwhile, worsening wildfire seasons, fueled by climate warming, are reversing decades of air-quality progress in this country. And ignoring and even stoking climate change, as Donald Trump’s administration is doing, will produce worse wildfire seasons. The country’s slide back toward its more polluted past “will become a steeper trajectory,” Joan Casey, an environmental epidemiologist at the University of Washington whose work helped expose the connection between wildfire smoke and dementia risk, told me.

The administration’s cuts to scientific research mean, too, that the impact of its deregulation may never be fully understood. In recent months, the government has pulled down some air-quality data and canceled grants; it also plans to dissolve a whole EPA division dedicated to studying how the environment affects public health. These actions create a sort of purposeful naivete: You can’t regulate what you can’t prove is harmful, and you can’t prove harm without research.

And you certainly can’t solve for what you don’t yet know is a problem. Newer findings about how air pollution may addle a body—by worsening mental health or triggering more cases of neurodegenerative disease, for example—haven’t yet been included in the EPA’s risk-benefit assessments of air-quality regulations, Casey added. “I think often we’re underestimating the true impact,” she said.

When I called Marianthi-Anna Kioumourtzoglou, an epidemiologist at Columbia University, she had just learned that the Trump administration had canceled her grant to study how impacts of climate change, including air pollution, alter cognitive function in aging people. (Earlier this year, too, she was dismissed from her appointment to the EPA’s Clean Air Scientific Advisory Committee, along with the rest of the panel.) Even so, the basics on air pollution have been studied enough that Kioumourtzoglou knows how current rollbacks will affect Americans: There will be “more heart attacks, more respiratory adverse health outcomes for sure,” she told me. “Our cognitive functions are going to be worse—the progression of Alzheimer’s, the progression of Parkinson’s.” Pollution-related depression and anxiety may go up. Even slightly increasing the risk or rate of any of these at the population level can diminish quality of life and, ultimately, productivity, she said. A sicker country is a poorer one.

Compared with smoking, for example, an individual’s risk of inhaling a dangerous amount of air pollution and then having their health affected because of it is relatively small, she told me—but “the problem is that few people smoke, and everybody breathes.” If a portion of the population’s cognitive function is diminished, even a little bit, the overall impact is enormous.

Kioumourtzoglou wonders, too, how much further the Trump administration will push the idea that air pollution should not be a concern to Americans. When the Heritage Foundation published a report in December that made the radical case that no definitive link exists between air pollution and poor public-health outcomes, she disregarded it. But after watching other Heritage Foundation goals be enacted, she is concerned that its rationale could be taken seriously by the current administration. The Heritage report attempts to cast doubt on the validity of decades of science by, in part, arguing that studies linking air pollution to health effects fail to prove causation, because they’re not randomized or controlled. (After this story was published, Diana Furchtgott-Roth, the director of Heritage’s Center for Energy, Climate, and Environment, said that the report was intended to guide federal policies and that it showed that “no causal link between particulates and heart attacks and deaths.”)

This is an attack not just on air-pollution research but on an entire scientific approach. Most public-health research is observational by necessity, because exposing people to air pollution in a lab setting to see how sick they get, say, wouldn’t be ethical. Instead, scientists gather data from already-exposed populations and try to parse out how different variables affected people’s health. Over decades, researchers have developed biostatistical methods to determine causal relationships from large groups of studies.

When EPA scientists and regulators link a pollutant and a health outcome, “they’re not making that assessment on one or two or three studies. It’s decades of scientific publications,” Corwin Zigler, a biostatistician at Brown University who served on an EPA scientific advisory panel on air pollution under the Biden administration, told me. He wasn’t surprised by the logic behind the Heritage Foundation report: The leader of the previous Trump administration’s air-pollution advisory panel had begun to sow doubt about basic air-pollution research. In response, the National Academies of Sciences, Engineering, and Medicine undertook a major review of the way the EPA assesses causal relationships, and though it recommended that the EPA’s process be more transparent, it found its methods scientifically robust. Zigler said he has no doubt that particulate matter is causing harm at current levels in the United States: “That’s the scientific consensus. That takes very seriously all of the limitations of any given scientific study.”

Studies about how entire populations are harmed by air pollution are framed in probabilities and percentages, but they represent a multitude of individuals for whom daily living has been made tangibly worse. For Lee, the Mount Sinai pulmonologist, work became personal a few years ago, when her son, now 5, began having asthma attacks that would send him to the emergency room. Asthma is a common-enough ailment that an attack might seem like a routine and manageable health issue. But anyone who’s had a severe one will tell you differently. Over years of reporting on air pollution, I’ve had asthma attacks described to me as feeling like someone is stepping with their full weight on your ribcage, or as though you are suddenly a fish out of water, suffocating on land. It’s a traumatic event. Lee, knowing what she does about air pollution, decided to move her family from New York City to the suburbs a year and a half ago; they haven’t been to the emergency room since.

“Clearly, we know that where you live determines your health,” Lee told me, but few people can make a choice like she did, to upend their life to breathe cleaner air. The Trump administration is also cutting the programs intended to address exactly these geographic disparities, while working to make the air worse for everyone. EPA Administrator Zeldin has said these rollbacks are part of the administration’s plan to “unleash the Golden Age of American prosperity.” But prosperity does not mean choking to death in one’s own home or depriving a child of cognitive capacity. Whatever wealth is promised here is narrowly disbursed at others’ expense.