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The EPA's big crackdown on smog, explained

David McNew/Getty Images

The lobbying battle around smog has been one of the most bitter environmental fights of the Obama era. For years, public health advocates have argued that cities like Los Angeles still have dangerous levels of smog, a leading cause of respiratory illness for millions of Americans. Industry groups, meanwhile, have countered that tightening the existing smog standards would be exorbitantly expensive.

On Thursday, the Environmental Protection Agency finally weighed in, setting stricter new standards on ground-level ozone pollution, the key ingredient in smog. And it appears industry has won a partial victory here. The EPA has tightened the ozone standard moderately, but not nearly as much as environmentalists and some health experts were calling for.

US counties are currently supposed to keep ozone levels in the air below 75 parts per billion (although many still don't). The EPA now says even those levels are unhealthy, so it's lowering the legal limit to 70 parts per billion. Hundreds of counties will have to reduce pollution over the coming decades in order to comply.

The EPA didn't go nearly as far as it could have here. Its scientific advisory panel had recommended setting the limit somewhere between 60 and 70 parts per billion and noted there was some evidence that even 70 would have adverse health effects. Environmentalists and public health groups wanted a more stringent standard at the lower end. But manufacturers, refiners, and other industry groups insisted that tightening too much would cost tens of billions of dollars and force factories to relocate. They would have preferred no action at all, but they're a lot happier with 70 than they would've been with 65 or 60.

This isn't the first time the Obama administration has tread cautiously (or sold out, if you prefer) on the ozone rule. Back in 2011, EPA scientists first presented evidence that the standard should be updated. But fearing a backlash, the White House delayed any final rule until after the 2012 election. Indeed, in a sign of how treacherous the politics around ozone are, the White House has barely said anything about today's rule.

What is ozone — and why is it a problem?

The downtown skyline is enveloped in smog shortly before sunset on November 17, 2006, in Los Angeles, California. (David McNew/Getty Images)

Ground-level ozone — the main ingredient in smog — is formed when pollutants such as nitrogen oxides from cars and power plants interact with heat and sunlight. The resulting pollution can "trigger a variety of health problems including chest pain, coughing, throat irritation, and congestion. It can worsen bronchitis, emphysema, and asthma." High levels of ozone can also damage crops and farms.

The American Lung Association estimates that 140.5 million Americans live in areas with unhealthy levels of ozone, putting them at higher risk for respiratory diseases. During the summer, local agencies issue"code red" alerts for cities if smog levels spike, warning those with heart or lung disease to avoid any strenuous activities.

The emissions that create ground-level ozone come from a variety of sources: cars and trucks, refineries, power plants, factories, oil and gas wells. Ozone levels are also partly dependent on the amount of heat and sunlight around. And in California's Central Valley, weather patterns tend to trap pollutants, leading to unusually high levels of smog.

(By the way, when ozone is near the Earth's surface, it acts as a lung irritant. But ozone high up in the stratosphere actually protects us from the sun's harmful ultraviolet rays. So too much ozone on the ground is bad, but too little ozone up high — an "ozone hole" — is also bad.)

Why is the EPA regulating ozone?

gina mccarthy

Environmental Protection Agency Administrator Gina McCarthy. (Win McNamee/Getty Images)

Under the Clean Air Act, the EPA is required to conduct a review of its national ozone standards every five years and update them as needed to protect human health. By law, the EPA is not supposed to consider costs when crafting these rules.

Back in 1997, the Clinton administration set the standard at 84 parts per billion. Then, in 2006, the EPA revisited the science on ozone and health and recommended a lower level of 60 to 70 parts per billion. This was based on new data, as researchers realized ground-level ozone might actually be killing people, not just causing respiratory problems.

In 2008, the Bush administration proposed a less stringent standard of 75 parts per billion. Groups like the American Lung Association sued to stop the Bush rules, which they claimed were too weak, unsupported by science, and would lead to thousands of unnecessary deaths and cases of respiratory disease.

After coming into office, President Obama promised a fresh review. In 2011, the EPA's scientists again proposed a limit between 60 and 70 parts per billion. But industry groups warned that tightening further could cost billions, and the White House decided to postpone any new ozone rules until after the 2012 election. Obama's then-chief of staff, William Daley, was reportedly nervous about the impact the rule might have on industries in swing states.

Outraged environmental groups filed lawsuits to force Obama to comply with the law. The courts agreed and ordered the EPA to come up with a final rule by October 1, 2015. That brings us to today.

How will these new standards work?

The EPA is proposing to tighten the standard for ozone in the air to 70 parts per billion, measured over an eight-hour period. Every county in the United States will have to be in compliance by 2025.

At the moment, there are 241 counties that are over that limit:

(Environmental Protection Agency)

Many of these counties were expected to reduce their ozone levels in the coming years anyway, thanks to other pollution rules the EPA had already put in place (including the Cross-State Air Pollution rule, the Clean Power Plan, and new vehicle standards). But others will have to do additional work to get below the limit.

By 2017, if any county still has ozone levels over the 70 ppb limit for an extended period, the EPA will deem it a "non-attainment area." States then have to figure out how to reduce pollution in these counties, which could take anywhere from 3 to 20 years. Areas with the worst smog, like Los Angeles, tend to get more time.

States have a lot of different options for cutting pollution from non-attainment areas. They might, for instance, require anyone hoping to build a new factory or power plant to go through extra permitting hoops, adopt stricter new pollution-control technology, or even pay to offset their emissions. In extreme cases, they might have to put in place congestion plans to reduce vehicle emissions.

In practice, some researchers have found, factories often end up moving to counties with less smog as a result of these plans. That reduces the concentration of local pollution, which eases the health impact.

In its final analysis, the EPA calculates that stricter standards would save thousands of lives and lead to fewer heart attacks, asthma attacks, and other respiratory illnesses. Many of those benefits come not just from cleaning up ozone, but from a corresponding reduction in particulate matter pollution. All told, the agency estimated that an ozone standard of 70 parts per billion would produce between $2.9 billion and $5.9 billion in annual health benefits by 2025 (in today's dollars).

Still, environmental groups argue that the EPA should've gone even further. "The EPA is legally obliged to set a standard based on public health," said Gretchen Goldman of the Union of Concerned Scientists in a statement. "[The scientific advisory board] said in its recommendation to the agency that a 70-ppb rule may not protect public health with an adequate margin of safety."

"There's a real public health cost of a weaker ozone standard," she added," and that cost falls hardest on the most vulnerable—the elderly, young children and those suffering from respiratory problems.

How much will these regulations cost?

Morning rush hour traffic moves along the 60 freeway on March 14, 2008, in Riverside, California. (David McNew/Getty Images)

The short answer is that it's still a bit unclear. The EPA estimates that an ozone standard of 70 parts per billion would cost companies around $1.4 billion per year by 2025 (in today's dollars). But outside analysts say it's worth being skeptical of any cost predictions right now.

In part, that's because the rule takes a while to implement. It will take until 2017 for the EPA to figure out which counties are actually in non-attainment. States will then have a few more years to come up with cleanup plans. Until we know what those look like, it's hard to gauge costs.

"Even after a proposal is signed, cost estimates will be little better than guesses," writes James McCarthy of the Congressional Research Service.

If the rule does end up costing $1.4 billion per year, as EPA thinks, that's considerably lower than the estimated health benefits, though obviously the companies that bear those costs aren't pleased with that trade-off. The American Chemistry Council has warned that a stringent ozone rule could thwart plans for factories and petrochemical plants that were hoping to take advantage of cheap shale gas in fracking areas. These groups have asked EPA to focus on fully enforcing its 2008 standard before rolling out a new one.

Industry groups also point out that this is just one of a number of new EPA rules that have been proposed in recent years. There are forthcoming rules on to curtail mercury pollution from coal plants. There are the Obama administration's new climate regulations to cut carbon dioxide emissions from the electricity sector. And now this.

It's worth adding a caveat to any predictions of doomsday: Historically, many pollution regulations end up costing less than originally estimated because new, unforeseen technologies helped companies adapt. That could easily turn out to be the case here: New techniques to reduce ozone-forming emissions are already popping up in the oil and gas sector.

Republicans will try to fight this new ozone rule in Congress. Last September, Sen. John Thune (R-SD) introduced legislation that would prevent the EPA from updating its ozone standards until at least 85 percent of counties that aren't meeting the old Bush-era standard are in compliance. Expect bills like that to get a lot of attention.

Is the air in the US getting better or worse?

Better. As the chart below shows, the six most common air pollutants in the US have all fallen 72 percent since 1970 — due, in large part, to the Clean Air Act.

(American Lung Association)

Over that same period, the US economy has grown 219 percent, the number of miles we drive has grown 165 percent, and the amount of energy we use has grown 47 percent.

So that's the very broad view. In the past, at least, the United States has been able to curtail air pollution and still get much, much richer.