Everybody knows that what happens in Vegas stays in Vegas, but the folks at the Environmental Protection Agency never got that memo. Or, if they did, they apparently believe it doesn’t apply to air pollution.

To see why, let’s start with the 1990 Clean Air Act. With some justice, it’s often credited with improving America’s air quality by enforcing the removal of certain toxic pollutants. One such pollutant is ozone, which is great up in the atmosphere, where it helps shield the Earth from solar radiation, but which causes serious respiratory problems closer to the ground.

To give a sense of how much less ozone there is in the air today, Congress in 1979 set a National Ambient Air Quality Standard for ozone at 120 parts per billion. Today, that number is set at 70 ppb.

That’s great, but we have effectively reached a point of diminishing returns, where further reductions in the standards are much costlier than in the 1970s, and any further health benefits are more questionable and less measurable. Yet rather than maintain its past successes, the EPA has in recent years been aggressively trying to squeeze out further reductions.

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This is where the Clean Air Act section with the Mr. Rogers-esque name, the Good Neighbor Provision, comes into play.

The Clean Air Act is structured so that the EPA sets the air quality standard, but the states determine how to implement that standard within their own borders. Under the Good Neighbor Provision, state implementation plans must also ensure that their airborne pollutants do not “contribute significantly” to non-attainment, or difficulty maintaining, the standards in other states. If the upwind state’s plan fails to mitigate pollutants contributed to downwind states struggling to meet the standard, the EPA can reject the state plan and replace it with the agency’s own federal implementation plan.

Nevada is a small state, but we do have the nation’s highest mineral production. We also have a cement factory in Fernley—not the cleanest industry, but it plays a critical role as one of the leading cement suppliers for infrastructure projects in the western United States. Yet all in all, Nevada is mostly empty, as anybody who has ever driven between Las Vegas and Reno can tell you.

Las Vegas, and more generally Clark County, is a genuine metropolis, but it’s also a desert oasis. There are no other major cities near Clark County. Neighboring California is much more densely populated, but the Sierras act as a natural barrier that largely protects California from out-of-state pollution (although, given pollution patterns, it is more accurate to say that the Sierras protect Nevada from Californian pollution, rather than the other way around).

Thus, under the climate models that Nevada prepared, relying on EPA’s 2018 guidance, Nevada’s ozone emissions did not even constitute 1 percent of the EPA’s 70-ppb goal in any downwind locality struggling to meet the ozone standard. Given that Nevada’s contribution of ozone to such areas was either negligible or nonexistent, it was clear that Nevada industry does not “contribute significantly” to any other state’s challenges in meeting the ozone standard.

So it came as a shock in 2022 when the EPA announced its intention to reject Nevada’s plan and to impose EPA’s own plan in its stead, more than three years after Nevada’s submission, and more than two years after the EPA’s statutory deadline to reject Nevada’s plan had passed. The EPA now claimed that new modeling, developed after the agency’s statutory deadline to respond, indicated that Nevada was projected to contribute greater than 1 percent of the standard to two counties in Utah with elevated ozone levels.

But even by the EPA’s own numbers, even if Nevada’s ozone emissions were entirely eliminated, these counties would be barely any closer to the standard.

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This is without even considering that, even under the new modeling, Nevada’s contribution still fell well under the 1-ppb threshold that the EPA originally suggested in its 2018 guidance. Even Utah considers the agency to have overstepped here.

Nonetheless, the EPA used these findings to disapprove Nevada’s plan and tried to seize control with a federal plan instead, taking action against the cement plant up in Fernley. The EPA’s plans became embroiled in litigation, not only in Nevada, but nationwide.

The litigation went badly for the agency, with courts reversing similar actions against Kentucky, Mississippi and Texas. The EPA suffered perhaps the greatest blow in June 2024, when the Supreme Court issued a nationwide stay against the EPA’s implementation of its Good Neighbor Plan.

Given this fraught recent history, and the egregious way in which the EPA has sought to encroach upon Nevada’s sovereignty, it is refreshing to see that the agency has proposed to reverse its disapproval and restore Nevada’s state implementation plan.

This still needs to be finalized, but if the EPA proceeds as planned, this will be a victory years in the making, not only for Nevada’s economy, but also for Nevada’s ability to govern its own affairs.