PM2.5 Air Pollution Is Still Killing Thousands of People in the US

Soot kills. Still! Even in America, even in 2019. Those suspended fragments and droplets smaller than 2.5 micrometers across, small enough to be inhaled into the deepest recesses of the lungs and slip into the bloodstream—that’s soot. Or PM2.5 in technical terms. Breathing it in can inflame airways, triggering respiratory troubles, heart problems, even dementia. And, as study after study have shown, these adverse health effects can trim years off a person’s life.

The situation is most dire in China, India, and other parts of Southeast Asia. Yet even in the US, which has stricter laws and cleaner air, the levels of particulate pollution permitted by the Environmental Protection Agency still claim the lives of thousands of people every year. That’s the message behind a massive new study published today in JAMA Network Open. The investigation combined EPA air quality data with a decade of medical records for 4.5 million US veterans to find links between chronic PM2.5 exposure and nearly 200,000 deaths.

The data suggests the standards might not be strict enough, says Ziyad Al-Aly, a clinical epidemiologist at Washington University and one of the study’s co-authors. “If you do the math, it tells us we could save at least 200,000 lives if we cleaned the air further,” he says.

These results track well with previous research, including a 2017 study among Medicare recipients that found the more soot raining down in your zip code, the higher the death rates. A study published in August connected surges in deaths across 652 cities around the world to spikes in PM2.5. This latest study adds the first ever links between particle pollution and deaths from chronic kidney disease, hypertension, and dementia. It’s the kind of epidemiological study that under normal circumstances would contribute to the mounting evidence that regulators need to do more to reduce fine particle pollution. But this is 2019 and nothing is normal.

The Clean Air Act requires that every few years a group of independent scientists sit down and review all the evidence that regulated air pollutants might be causing adverse health effects. That group, called the Clean Air Scientific Advisory Committee (or CASAC) then files a report to the EPA, and the agency decides if the existing standards are good enough, or if stricter measures need to be pursued. Under the Trump administration, this process has been turned upside down.

Before Scott Pruitt resigned from his post as EPA chief in 2018 amid ethics scandals, he revamped the agency’s policies on who could serve on scientific advisory panels. Pruitt’s successor, Andrew Wheeler, then used those policies to fire all the scientists who had been appointed to the CASAC in 2015 and replace them with a pool of consultants, many with ties to the oil, gas, and chemical industries. He also disbanded a particulate matter sub-committee that in the past had contributed expertise to the CASAC’s review and recommendation process.

In October 2018, the EPA released a draft review of the public health impact of fine particulate pollution. After assessing nearly 2,800 studies in its 1,900-page report, the agency concluded that the science supported lowering the annual exposure limit for PM2.5 by as much as one-third. CASAC is now trying to block that assessment. In a December meeting, and later in a draft letter to Wheeler, the group’s chair, Louis Anthony Cox, argued against its findings, suggesting that the kinds of studies CASAC has long relied on, including epidemiological studies that don’t show direct causality, should be tossed out. Scientists have since publicly decried that claim as being “fringe” and ignoring long-established scientific consensus.

The situation puts the EPA in an unusual predicament. It could accept Cox’s opinion and keep existing air pollution standards that risk public health. Or it could ignore his committee’s advice and potentially erode public confidence in the science advisory process. At least one outside group is advocating for the latter. The disbanded ex-CASAC experts, who in an unprecedented move regrouped to form a parallel independent panel with support from the Union of Concerned Scientists, conducted their own review in line with the EPA’s draft. Last month, at a CASAC public meeting they presented a letter to Administrator Wheeler offering their assessment of the evidence, and urging him to “follow the science.”

John Balmes, a public health researcher at the University of California, Berkeley, and one of the 20 dismissed scientists to sign on to the letter, says if Cox gets his way, few studies will be left to support a stricter PM2.5 standard. “They just don’t want to hear any of the new scientific evidence,” he says. Yet the data keeps accumulating. Today’s JAMA study, which he was not involved in, provides another strong argument for cutting down on particulate pollution. “It’s a big study, it’s a good study, and it’s just more support of what we already know.”

The CASAC will meet again in December and offer its recommendations to the EPA Administrator. In the end, it’s Wheeler who will have ultimate authority over whether the agency sets a new standard for PM2.5. Balmes says he and the rest of his merry band of disbanded scientists didn’t go through the pains of a review because they think it’ll convince Wheeler to update the soot standards. Rather, he’s betting it will come in handy for any lawsuits that might arise if the agency sticks with the status quo.

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