Back in 2007, a panel of scientists decided that to protect public health the national ambient air quality standard for ground-level ozone standard should be between 60 and 70 parts per billion. The scientists were part of the U.S. Environmental Protection Agency's Clean Air Scientific Advisory Committee (CASAC), a group of air quality and health experts selected to advise the agency on air pollution standards. That was 2007. Last week, their recommendation was finally acted upon. But does the science still say that 70 ppb is enough?
When I was working in academia several years ago, I studied ozone and its association with human health effects. I read through dozens of papers quantifying this relationship and I saw in my own data that ozone had real health impacts. The unique thing about ozone compared to other ambient air pollutants is that it spreads far and wide. You don't need to live or work in a city center to be subject to its effects. If it's a bad air day in Queens, it's likely also a bad air day in Greenwich, Connecticut. Because of this, large portions of the populations are subject to ozone's health effects, including respiratory irritation, asthma aggravation, and the potential for permanent lung damage. These health outcomes disproportionately affect sensitive populations including children, the elderly, and individuals with lung diseases.
My research was part of hundreds of studies that go into the EPA's exhaustive assessment of ozone science that the agency uses to set the standard. The Integrated Science Assessment, along with CASAC's advice, help ensure the EPA can set a standard based on public health every five years, as its obligated to under the Clean Air Act. Despite this obligation, the 2007 EPA set the standard at 75 ppb, higher than the CASAC recommendation. Since then, there's been a lot more science on ozone's relationship with health (including mine).
In 2011, the Obama administration decided to take another look at the ozone standard, even though it had been less than five years since the previous standard was set. CASAC's 2007 recommendation was sent to the White House for approval, but the administration chose not to update the standard at that time despite the scientific evidence. Instead, the administration opted to wait until the next cycle of ozone standard review--the one that just completed last week--to consider whether the standard needs tightening.
When the administration took more than the required five years to update the standard, environmental and medical advocacy groups sued. The EPA was then under a court-ordered deadline to release a rule by October 1, 2015. This time around, EPA's science advisors again recommended setting an ozone standard in the range of 60 to 70 ppb, but now they added some additional information. The scientists concluded that 70 ppb might not be protective of public health with an adequate margin of safety, as the Clean Air Act requires. They said in their letter to the agency this year that with a 70-ppb standard there is "substantial scientific evidence of adverse effects ... including decrease in lung function, increase in respiratory symptoms, and increase in airway inflammation." This means that even if the whole country met a standard of 70 ppb, we would still observe health impacts from ozone pollution.
When the EPA announced a final rule of 70 ppb last Thursday, it did so with this knowledge--knowledge that science suggested the standard should probably be lower. We know that a lower standard would have been more protective of public health. In fact, EPA's own analysis showed this. And we know that vulnerable populations will be especially susceptible to these health outcomes.
On a press call on Friday, the administration defended its decision but saying that it put more weight in clinical studies than in epidemiology studies in setting the standard at 70 ppb. Both study types were included in the agency's science assessment and were considered by CASAC and some questioners claimed that weighting clinical studies more heavily than epidemiologic studies ran counter to the methods used by EPA in setting air pollution standards in the past.
Industry groups have already lined up to express their displeasure with the rule, after pouring tremendous resources into fighting any reduction in the standard. The American Petroleum Institute (API), for example, used questionable methods to determine what counties won't be able to meet the new standard. The National Association of Manufacturers pulled out all the stops, running misleading ads in television commercials, on radio, and online, claiming that any tightening of the ozone standard would cost tremendous amounts of money and jobs and the country won't be able to meet the standard anyway because of background concentrations and overseas transport of ozone.
If these arguments sound familiar, it's because they are. Back in 2008, the EPA under the Bush Administration tightened the ozone standard from effectively 84 ppb to 75 ppb, a standard that was much weaker than what the science advisors had recommended. Still, this was too high for NAM and the U.S. Chamber of Commerce. The new standard "could have a devastating effect on manufacturing employment," said John Engler, then-chief of the trade group in 2007. Bryan Brendle, NAM's director of air quality policy, was reported to have said there is no evidence of increased health benefits from a lower standard (login required). NAM also released data on the cost of the rule, despite the fact that the law requires that the EPA consider public health and not costs in setting the standard. Meanwhile, the U.S. Chamber of Commerce pressured the EPA to consider foreign emissions in its 2008 rulemaking.
These arguments were wrong then. And they are demonstrably wrong now, as we have the hindsight to look at the impact of that 2008 standard. Analysis after analysis has shown the economic benefits of health-based ambient air quality standards. Hardly a "devastating impact." And new standards have always lead to cleaner air (check out this neat EPA graphic showing that 90% of counties not meeting the 1997 ozone standard now meet it). The standards have made our air cleaner and we can literally observe that in the data. The arguments didn't work in 2008, and they don't work now.
Seventy parts per billion is an improvement. Many more people will be protected than were under the 75 ppb standard. But we also know that the administration could have done more to protect Americans from ozone pollution in accordance with the scientific advice it received. Now, we will need at least another five years and another science-accepting administration to get a more protective standard. In the meantime, like I did, scientists will continue to study those bad air days.