In 1993, a landmark public health study exposed a simple yet startling fact: particles kill. By analyzing over 14 years of air pollution and health data from more than 10,000 individuals, scientists found that Americans living in cities with dirtier air were dying faster than those living in cities with cleaner air.

The Harvard Six Cities Study, along with many others, helped pave the way for strengthened U.S. regulations on air quality under the Clean Air Act. The results have since been corroborated around the world, with different populations and at different exposure levels. The most recent findings suggest that the harmful effects of particulate matter persist even at levels below current U.S. ambient air quality standards. And early death is just the tip of the iceberg: particulate pollution has been linked to a plethora of other adverse health outcomes, including asthma exacerbation, lung cancer, diabetes and even reduced IQ and neurological problems.

Industries and ideologues bent on deregulation have long sought to block the use of this science in policy decisions. Now, these forces are seizing opportunities under the Trump administration to dismantle the scientific foundations that protect us from air pollution. The result could make it cheaper and easier for industry to pollute, putting our lives and health at greater risk—especially communities of color who are already disproportionately exposed to air pollution and its health impacts.


In the regulatory process of the U.S. federal government, decision makers must often demonstrate that the benefits of a new public health protection will outweigh its costs. Right or wrong, this cost-benefit analysis framework frequently underpins the nation’s ability to protect the public from harms. It turns out that particulate matter features prominently in this math—accounting for one third to one half of the estimated benefits of all significant federal regulations between 2003 and 2012.

It’s little wonder, then, that corporate interests—including the fossil fuel, auto, and tobacco industries—have been searching for ways to undermine the scientific link between particles and death since at least the 1990s. (Decades prior, in the 1940s, the fossil fuel industry also attempted to discredit evidence that burning fossil fuels produces air pollution in the first place.) Now, deregulation sympathizers in the White House and the Environmental Protection Agency, many with close ties to industry, are waging an unprecedented assault on the science substantiating the health impacts of air pollution.

So far, the strategy appears to be a three-pronged attack. First, the Trump administration is narrowing the scope of what can be counted as benefits from environmental regulations by disallowing avoided deaths from concomitant reductions in particulate matter and other emissions.

For example, a recent proposal to reverse the legal foundation underpinning the EPA’s Mercury and Air Toxics Standards for coal- and oil-fired power plants hinged on this exclusion. Similarly, in its proposed replacement for the Clean Power Plan—a legally required standard to address global warming emissions—the Trump administration plans to consider only the benefits that accrue from carbon dioxide emissions reductions, shirking the billions of dollars of additional co-benefits anticipated to come from avoided particulate exposure. Why? Because it’s the only way the math will work out in industry’s favor.

Second, EPA leaders are upending the agency’s long-standing process for setting the National Ambient Air Quality Standards. Since their establishment in 1971, the Clean Air Act requires periodic review of the science upon which the standards are based and of the standards themselves to ensure adequate protection of public health. The standards for particulate matter—one of six criteria air pollutants—are currently under review.

Last year, former EPA Administrator Scott Pruitt introduced a new policy that resulted in the removal of scientists with EPA grants, while allowing others with direct ties to regulated industries, to serve on EPA’s advisory committees. Last October, the agency completely disbanded the Particulate Matter Review Panel. Without them, the only external scientific voice left is the seven-member Clean Air Scientific Advisory Committee, which EPA leaders had already gutted and replaced with less-experienced individuals.

In an unprecedented move, the committee itself acknowledged this shortcoming, admitting that its members didn’t have the expertise needed to review the particulate matter standard. Now, the EPA is in a tough spot. To fulfill the Clean Air Act mandate, it needs access to the best available science on particulate pollution and health impacts. But the Trump administration has left the agency with dismantled science advice and a flawed process—conditions that will make it easier for EPA Administrator Andrew Wheeler to make a political, rather than scientific, decision.

Finally, the Trump administration is trying to restrict the science that can be used in regulatory decisions. Under the auspices of promoting scientific transparency, the proposed EPA rule “Strengthening Transparency in Regulatory Science” would invalidate the use of public health studies—such as the Harvard Six Cities Study—by requiring that the underlying data be made public. Scientists cannot legally and ethically release the individual health data behind their studies, and they shouldn’t have to.

The scientific community has long applied rigorous peer-review processes without compromising health data confidentiality. Unsurprisingly, the proposed rule has seen near unanimous opposition from the science community. Yet it is expected to be codified in EPA’s forthcoming final rule. And just last month, the White House issued guidance with yet further restrictions, suggesting that studies used in federal regulations must not only rely on publicly available data but also be reproducible.

This raises questions about how scientists can use data related to pollution events that cannot be ethically and feasibly reproduced, such as evaluating the health impacts of wildfires and chemical leaks.

This series of attacks aren’t a coincidence. They are part of the same strategy serving the same purpose: weaken the evidence for, and diminish the ways we can respond to, the fact that particles kill. Long on industry’s wish list, the dismantling of the science behind particulate pollution is now high on the Trump administration’s agenda.

The evidence that this is a strategy isn’t just circumstantial. An e-mail to EPA political appointees from a representative of the Heritage Foundation (a right-wing group funded by fossil fuel and tobacco industries), obtained via a Freedom of Information Act request from the Union of Concerned Scientists, asked: “Will [the Particulate Matter Review Panel] be disbanded and stopped before it rubber stamps more PM2.5 junk science, which would ruin the repeal of the Clean Power Plan?” (PM2.5 collectively refers to particles smaller than 2.5 micrometers, which are small enough to reach the depths of our lungs and even enter our bloodstream.)

The response from EPA leadership is redacted, so we don’t know if the administration agrees with this perspective. But with the review panel having since been disbanded, it certainly seems to be carrying out the motions.


The tactics on display here are similar—and, in many cases, identical—to those employed in historical and ongoing campaigns by various industries and ideologues to confuse the public, dispute scientific evidence about health risks posed by their products and actions, and impede regulations. Tobacco, acid rain, the ozone hole, climate change—and now, air pollution. This is not the first time our health and well-being are being sacrificed for short-term profits. And it won’t be the last.

It’s also worth remembering, however, that U.S. politicians and policy makers once treated air pollution as a bipartisan issue, putting the public before corporate profits in the 1970 legislation of the Clean Air Act and subsequent establishment of the National Ambient Air Quality Standards, which have saved millions of American lives and trillions of dollars.

Today, more than 40 percent of Americans still breathe unhealthy air, resulting in over 85,000 premature deaths each year—more than those due to road accidents and secondhand smoking combined. How high will these numbers climb if the Trump administration succeed in dismantling the use of particulate pollution in federal regulations?

We cannot allow this to happen. The scientific community and the public must speak up to demand that policy makers make choices that are informed by science and that protect us from harm. Ask your elected officials to support the Scientific Integrity Act, which would strengthen government agencies’ ability to make science-based decisions, and the For the People Act that would curb corporate influence on our decision makers. If the EPA proposes particulate standards that don’t align with science, provide public comments to the agency.

Most importantly, elect politicians who will stand up for science and prioritize our well-being over corporate profits. Because “nothing is as elemental, as essential to human life, as the air we breathe.”

The opinions expressed are those of the authors and do not reflect those of their institutional affiliations.