The World Health Organization is calling for sharp reductions in air pollutants that kill over 7 million people worldwide every year, including some 300,000 in the US.
In late September, WHO adopted new and stricter guidelines for six different poisons that commonly pollute the air. These include carbon monoxide, sulfur and nitrogen oxides, low-level ozone commonly found in smog and medium and fine particulates.
The size of a pollution particle in the air determines how harmful it is for human health. Fine particulates known as PM2.5 are about 2 1/2 microns in diameter — about 1/20 of the width of a human hair. These tiny but deadly toxins get inhaled through the lungs and enter the bloodstream where they circulate — just like oxygen molecules.
PM2.5 particles lead to the bulk of early deaths around the world. In the United States, the allowable amount of yearly exposure to fine particulates is more than twice what WHO now recommends.
WHO measures levels of particulates in the air over the course of a year, and has a separate standard for a single day. Prior to the new standards, WHO’s guidelines stated that exposure to 10 micrograms per meter cubed of PM2.5 was safe. They’ve now lowered the safe level to 5 micrograms.
“That's a pretty drastic reduction,” says Dr. Aaron Bernstein, pediatrician and interim director of the Center for Climate, Health and the Global Environment at Harvard University.
"[I]t's estimated about 8 million people are dying from burning fossil fuels that produce particulate air pollution every year. That’s 1 in 5 deaths."
“We know that particulate matter pollution is responsible for millions of deaths around the world every year,” Bernstein says. “Estimates vary, but a recent publication looked at just the particulate matter from fossil fuels — which, of course, is probably one of the bigger sources, if not the biggest source, depending on where you live — and it's estimated about 8 million people are dying from burning fossil fuels that produce particulate air pollution every year. That’s 1 in 5 deaths. So, we know that particulate pollution, particularly PM 2.5, is a big deal for death and, of course, a host of other health problems: asthma, chronic lung diseases, heart disease, stroke, even lung cancer, and I could go on.”
Press material from the World Health Organization suggests that perhaps 80% of the deaths from fine particulates could be prevented if the new standards are universally adopted, a figure Bernstein says is “not implausible.”
'[T]he good news, of course, is that most of that air pollution, in many parts of the world, is coming from burning fossil fuels, and that means we have an opportunity to not only prevent those deaths today, but also help address climate change."
“We have for a long time underestimated how many people's lives were being lost from air pollution,” he says. "And we know that so many people are living in polluted air that [is] in excess of what the World Health Organization [previously] said was safe. So ratcheting the level down — we could save a lot of lives here. And the good news, of course, is that most of that air pollution, in many parts of the world, is coming from burning fossil fuels, and that means we have an opportunity to not only prevent those deaths today, but also help address climate change."
In addition, Bernstein adds, there’s now clear evidence that people who have breathed high levels of PM2.5 air pollution over many years are more likely to die from a COVID infection. Colleagues of his at the the Harvard T.H. Chan School of Public Health found that breathing just one additional microgram per meter cubed over many years increases the chance of dying from COVID by 6% or 8% in the United States.
“That same particulate matter air pollution is going to increase your chance of dying from the seasonal flu, or from pneumonias, or other respiratory infections,” Bernstein adds. “This has been known for a long time. And so it wasn't surprising to many of us to see that it was true, in fact, with COVID, which for many people is a problem for the lungs.”
For many pollutants, especially particulate matter, medical evidence suggests that, in reality, there's no safe level of exposure, so it really becomes a question of trade offs, Bernstein says: How much can we reduce pollution levels and how much money is that going to cost?
"[W]hen you look at the health effects, and include the health effects and the costs of the harms of air pollution in your cost-benefit [analysis], it turns out that reductions below current levels are cost effective, that we actually would save money.”
“What's interesting is that, particularly in countries that have cleaned up a lot of air pollution, like the United States, even when you've done that, we still see [that] when you look at the health effects, and include the health effects and the costs of the harms of air pollution in your cost-benefit [analysis], it turns out that reductions below current levels are cost effective, that we actually would save money.”
When policymakers make rules to control air pollution, however, they’re quick to focus on the cost of cleaning up the air, while minimizing the benefits, Bernstein notes. As a result, laws don’t usually lower pollutants to levels the science recommends.
Nevertheless, the Clean Air Act “directs EPA to review the science and to set standards that are protective of health, including for vulnerable populations,” Bernstein says, “and so we can expect that EPA is likely to lower the exposure standard for particulate matter.”
But these efforts typically cause “a real political melee” because “polluters don't want to stop polluting so much, even if the pollution is causing pretty big harms,” Bernstein points out. “And there's a "huge equity issue here,” as well.
“In an era where we're all so focused on addressing systematic discrimination, it's hard to look at the data that makes so clear that if you're a Black American or Latinx American, not only are you exposed to way more of this pollution because of where you live and where those places are in relation to power plants and roads, you're the least responsible for producing it. And so it's this sort of double inequity."
"On the flip side of that, the more we can do to reduce pollution emissions, the more we’ll see reversal of historical injustices,” Bernstein concludes.