Air Pollution: Some Good News
Environmental data tends to be pretty grim. I can't remember the last time I read something encouraging about climate change, microplastic debris, wildfires, etc.
Last week though there was a barely noticed ray of hope.
If you scrolled past the stories about Joe Biden's memory, Donald Trump's legal drama, and American's newest sweethearts (plus a football game, featuring Usher), you would've discovered, on the digital equivalent of the back page, that the EPA just announced a new standard for air quality.
In this newsletter I want to describe why this announcement is good news.
Sorry to say, it's not unqualified good news. Air pollution will continue to be a health hazard. Some people will continue to be especially vulnerable. But the EPA's decision bodes well for the lungs of the planet and its residents.
The EPA announcement
On February 7, the EPA announced a strengthening of air quality standards. Specifically, the annual average for fine particulate matter (PM2.5) is being lowered from 12 to 9 micrograms per cubic meter (µg/m3).
What is PM2.5?
PM2.5 consists of any particles in the air that are 2.5 microns in diameter or smaller.
"PM" stands for "particulate matter". 2.5 microns is about 1/20th to 1/30th the diameter of a human hair (see EPA graphic below).
PM2.5 particles come from a variety of sources, including dust, wildfires, sea salt, and fossil fuel emissions. Any airborne particle that's small enough counts.
Although PM2.5 is often referred to as soot, the terms aren't quite synonymous. Soot is just one type of PM2.5 (specifically, carbon particles from sources such as the burning of fossil fuels).
Why is the new EPA standard important?
PM2.5 particles are small enough to penetrate the deep tissue of the lungs and, in some cases, enter the bloodstream.
The science is clear about some of the health impacts: Short-term exposure to PM2.5 exacerbates existing conditions such as asthma and COVID-19. Long-term exposure increases the risk of heart and lung disease, acute cardiac events (heart attacks and strokes), cancer, dementia, metabolic disorders (diabetes, high cholesterol, etc.), and premature death. That's not even a complete list.
The science also shows that some people are especially vulnerable, including children, the elderly, and people with compromised health. Individuals in low-income communities as well as communities of color are vulnerable too, because they tend to live and work in closer proximity to the sources of PM2.5 pollution, and their access to health care is more limited.
The photo above shows children playing in front of the CSX coal exchange in Curtis Bay, South Baltimore. For decades residents complained about pollution in their community as well as health problems such as asthma, but not until an explosion at CSX on December 30, 2021 did the state government, working with Johns Hopkins and other partners, launch a collaborative investigation into the quality of the local air. The results were published two months ago and prompted the state government to "confirm" that there's coal dust in the Curtis Bay community (and unacceptable PM2.5 levels). But the residents knew that already. They'd been wiping coal dust off their property for decades.
So, at first glance, the EPA's announcement seems like a boon. For the residents of Curtis Bay, and for the rest of the nation, a stricter standard seems to promise better health.
Why this newsletter doesn't end here
The EPA's new standard sounds impressive if you're thinking in terms of percentages. Changing the maximum yearly average from 12 to 9 µg/m3 represents a 25% reduction.
This change doesn't sound quite so impressive once you start thinking about the actual composition of your air. Depending on the type of PM2.5 and other factors, a change from 12 to 9 µg/m3 amounts to a reduction of less than 2 parts per billion.
This gloomier way of thinking raises two questions:
1. Could the EPA's new standard benefit public health, at least in theory?
2. Will the public actually benefit from the new standard?
The first question is a matter of statistics. Assuming PM2.5 levels of 12 µg/m3, would people end up healthier if you cleaned their air and PM2.5 levels dropped to 9 µg/m3? In a moment I'll talk a bit about research on the topic, including a study published three weeks ago.
The second question is a political one. The new standard is expected to have an immediate impact, but federal enforcement wouldn't begin until 2032. Meanwhile, industry groups are already complaining about the EPA's decision, and no law prevents some future administration from reverting to the earlier standard, or worse. Near the end I'll discuss what we can do to protect the new standard, and whether it makes sense to call for a more rigorous one.
Could the EPA's new standard benefit public health?
Since 2010 alone, more than 10,000 studies have explored the health impacts of PM2.5, and I intend to review every one of those studies here.
I'm joking of course, but not about the voluminousness of the literature. Rather than trying to summarize how much we've learned about the topic, here are three ways to approach the narrower question of whether the new standard could, in theory, benefit public health:
(a) Step up, ask an expert.
I reached out to Dr. Jonathan Buonocore, a Boston University professor who specializes in in environmental health. (We had hoped to talk by phone but were unable to coordinate schedules.)
Dr. Buonocore explained to me via email that the EPA's new standard would translate into health benefits, noting
"there is good evidence that lowering the standard will have a meaningful reduction in air pollution and the consequent health impacts."
This tracks with what other experts have been saying publicly since the EPA announcement on February 7.
(b) Step in, read the studies.
Obviously I didn't read 10,000+ studies but rather just of few of relevance.
I focused on studies investigating the long-term health impacts of exposure to annual PM2.5 levels that ranged from lower than 9 µg/m3 on average to somewhat higher than 12 µg/m3, a range that's roughly comparable to what Americans tend to experience. (81 countries have annual levels exceeding 12 µg/m3 on average, and so I skipped over many studies exploring health effects for levels much higher than ordinarily found in the U.S.)
I also focused on studies that calculated the long-term impact of incremental changes – typically the effects of each 1µg/m3 increase in PM2.5. (I skipped over many studies looking at larger increments of change, such as 5 µg/m3.)
What I found is substantial evidence that a shift from 12 to 9 µg/m3 per cubic meter per year, on average, would have health benefits.
The most recent example I saw was published just three weeks ago in the journal Environmental Health Perspectives. A research team led by Dr. Markey at the Water and Air Quality Bureau in Ontario looked at the impact of PM2.5 exposure and one other pollutant on the respiratory functioning of 2,001 newborn babies in 10 Canadian cities. The average exposure was just under 9 µg/m3; the minimum was just under 2. After controlling for a host of maternal and neonatal variables, Markey and colleagues calculated that each 1 µg/m3 increase in PM2.5 was associated with a significantly greater risk of respiratory distress.
Although this should considered a small study, given the amount of statistical work that was done, the results are consistent with data I've seen on cardiovascular, pulmonary, and metabolic outcomes. Evidently small changes in PM2.5 levels, within the range that most Americans are exposed to each year, lead to better health.
If each 1 µg/m3 increase in average yearly PM2.5 levels is beneficial, it follow that the EPA's change may have public health benefits.
(c) Step back, listen to the authorities.
Exactly how much will we benefit from the new standard?
The EPA claims that the 9 µg/m3 standard "will" save lives and money, by "preventing up to 4,500 premature deaths and 290,000 lost workdays, yielding up to $46 billion in net health benefits in 2032."
Sad to say, the benefits of the new standard can't be estimated, with confidence, to anything near this level of precision.
The EPA's projection relies on dozens of assumptions pertaining to the accuracy of measurement, county-level changes in air quality over the next 8 years, unknowns such as the extent of wildfire activity, industry compliance with the new standard, and so on. Providing such specific projections may be good political strategy, but it's not very persuasive science.
In sum, the EPA's new standard should benefit public health (and save lives and workdays) but it's impossible to quantify with any confidence how much the benefits will be.
Should the EPA implement a more rigorous standard?
World Health Organization (WHO) guidelines call for annual PM2.5 levels of no more than 5 µg/m3. The new EPA standard allows the levels permissible in the U.S. to be nearly twice as high. Would the U.S. benefit from a more rigorous standard?
Dr. Buonocore and other experts would say yes. As Dr. Buonocore noted in his email to me:
"There is good evidence that there are health impacts of exposures below 9 µg/m3, so there would still be a way to go before we reach a level with zero health impacts."
The implication is that we need guidelines at least as stringent as the WHO's.
As the WHO explained in 2021, its 5 µg/m3 per year guideline was based primarily on data linking PM2.5 exposure to mortality. In these studies, effects were observed for yearly averages below 8 µg/m3, but not within the range of roughly 3 to 5 µg/m3.
The EPA itself, in a technical document, notes differential health impacts in yearly averages that range from 5 to 10 µg/m3. It follows that an upper limit of 5 µg/m3 would be healthier than the EPA's new 9 µg/m3 standard.
Broadly speaking, many studies show that at the lowest levels, slight changes in annual PM2.5 levels have the biggest impact on health.
In other words, if air quality is quite poor, a slight increase would have little or no impact. If air quality is relatively good, a slight increase in PM2.5 levels would have a stronger impact. This also suggests, albeit indirectly, that a 5 µg/m3 per year limit would be preferable to 9 µg/m3.
How low should we go?
I mentioned to Dr. Buonocore that the literature seems to point to a simple conclusion about annual PM2.5 levels: the lower the better. He responded
"that’s my read too. There’s a lot of “safe thresholds” that fall apart when you look more closely."
Although zero PM2.5 is impossible, owing to erosion, wildfires, and other natural phenomena, human activity has a substantial impact on ambient levels, and much can be done to improve the quality of our air. The EPA's new standard is a step in the right direction.
Why this newsletter doesn't end here either
So far, I've argued that the EPA's new standard will benefit public health, and that a more rigorous standard would be even more beneficial.
Unfortunately, EPA standards are politically vulnerable. The head of the agency, known as the EPA Administrator, is a presidential appointee and may seek to overturn, ignore, or delay prior EPA decisions that conflict with the current president's agenda. During the Trump administration, for instance, 112 environmental rules (mostly at the EPA) were rolled back.
(Even the new standard appears to have been influenced by political realities. The EPA has been careful to note, in several places, that most U.S. counties are already compliant with this standard – as if to say look, change is needed, but we're going to ask for as little as possible.)
I think we need to ensure that the new standard isn't rolled back. We should also press for a more rigorous standard, such as the WHO's 5 µg/m3 per year average, and we should insist on enforcement of the standard. (Enforcement is a huge concern. The EPA recently reported "widespread noncompliance" with regulations on toxic coal ash; long story short, the agency appears to have moved very slowly on this.)
How you can support air quality and public health
Although my newsletters are often nonpartisan, and I've sometimes criticized left-leaning organizations (NY Times) as well as individuals (Nicholas Kristof), here I would say that to the extent that air quality and other environmental health issues are important to you, you should vote Democratic.
I won't turn this newsletter into a political rant. If you're not a one-issue voter, you might agree with me here but still vote Republican because, on balance, that's a better choice for you.
As for this particular issue, Democratic leaders tend to advocate more strongly for environmental policies and practices that support public health.
Assuming these issues are of great importance to you, you would want a Democratic president, in part because the head of the EPA is a presidential appointee and always more or less ideologically aligned with the president.
You would also want a strong Democratic influence in Congress, as well as in state and local offices, since PM2.5 levels – and inequities in exposure – are influenced at all levels of the political process. Even in Maryland, where the state government has been predominantly blue for decades, it took years to engage the government in a systematic investigation of air pollution in Curtis Bay.
This brings me to my former M.Ed student Sam Eppler, a Democratic candidate for U.S. Congress in Texas's 24th District. Apart from being an amazing person and the youngest high school principal in the state, Sam is committed to a cleaner environment and believes, as he texted me recently, that
"one of the primary functions of government is to protect and support "public goods" like clean air, clean water, and green spaces to enjoy and recreate."
Meanwhile, the incumbent, Beth Van Duyne, joined other Republicans this past November in voting to cut the EPA budget by 39%. (This would be an extraordinary reduction. The agency might be better equipped to handle problems like noncompliance with toxic ash rules if its funding were increased rather than slashed.) Since taking office in 2021, Ms. Van Duyne has received one of the lowest scores on LCV's National Environmental Scorecard, which tracks congressional voting records on environmental issues.
Again, if you're not a one-issue voter, this advice may not work for you, but if you happen to live in the 24th District (an area extending between Dallas and Fort Worth), I would encourage you to vote for Sam Eppler. You can do it early (2/20 through 3/1) or on Super Tuesday (3/5).
(This message was paid for by no one. Nor was it written by an AI chatbot.)
I assume that most of you don't live in the Dallas-Fort Worth area. If you don't, but you're concerned about PM2.5 levels and other environmental issues, I encourage you to vote Democrat if you don't already – and, regardless of your political affiliation, push your representatives to support a cleaner environment (in part by negotiating a federal budget that doesn't cut EPA spending).
In the February 7 announcement, the EPA noted that it's currently modifying the way PM2.5 levels are monitored among people at increased risk of exposure owing to where they live. From an environmental justice perspective this is encouraging, but what does it mean concretely, and when will the change be implemented? Curtis Bay residents are already unhappy about the prospect of waiting 8 years for the new EPA standard to be enforced. How long will they have to wait for better monitoring of local PM2.5 levels? (The report I mentioned earlier was cautious not to delve into much quantitative detail.)
If you're interested in nudging the EPA, you can contact them directly here, or reach out to an environmental advocacy group, or just encourage your local congressional representative to support more rather than less EPA funding.
How you can support your own health
If you have concerns about air pollution, or PM2.5 contaminants in particular, technology may help. Portable air cleaners (PACs) can be effective in relatively air-tight rooms, as can the use of HVAC units with appropriate filters.
Behavioral strategies can be useful too. Experts recommend avoiding highly polluted areas, especially when exercising, and staying indoors when the Air Quality Index (AQI) is high.
You could also move to Iceland. With average yearly PM2.5 levels of 3.4 µg/m3, Iceland has the cleanest air of any country on the globe.
If you prefer not to relocate, I suggest that you simply avoid excessive pollution to the extent possible, consider technological support, and vote for a cleaner environment. By voting blue, you can keep this blue marble more blue than brown.
Thanks for reading!