Poli-Sci Perspective is a weekly Wonkblog feature in which Georgetown University’s Dan Hopkins and George Washington University’s Danny Hayes and John Sides offer an empirical perspective on the issues dominating Washington. In this edition, Hayes looks at new evidence of how air polluters tend to export their emissions to neighboring states. For past posts in the series, head here.

Watch out downwind--particularly if downwind is in another state. (F. Carter Smith/BLOOMBERG )

If you near a state line, you might be getting an unusually heavy dose of pollution from your neighbors across the border.

That’s the conclusion of a working paper by political scientists James Monogan, David Konisky and Neal Woods. They report that air polluting facilities in the United States are disproportionately likely to be located near downwind borders. When the breeze picks up, noxious emissions are hustled out of state and become someone else’s problem.

The pattern highlights one of the difficulties facing pollution control efforts in the country. States play a major role in implementing U.S. environmental policies, but they also have an incentive to export the environmental and health costs of economic development across state lines.

Cross-border pollution is not a new issue. In the early 1900s, Monogan and his co-authors write, Georgia sued a Tennessee copper smelter for “despoiling forests and orchards and creating health problems for residents of bordering counties in Georgia.” New Jersey in 2006 accused the Environmental Protection Agency of failing to regulate toxic emissions from a coal-fired power plant across the Delaware River in Pennsylvania. And several studies have argued that pollution levels tend to be higher near borders than in the interior of a state, a phenomenon referred to as “state line syndrome.”

But state line syndrome doesn’t appear to stem from lax enforcement or state regulatory policy, the authors write. Instead, it may simply be that higher levels of border pollution occur because of the strategic location of air polluters, such as power plants and industrial facilities.

To investigate their hypothesis, the authors first identified from EPA records the location of 16,211 major air polluting facilities in the United States. They also charted the prevailing wind direction along state lines, on the assumption that downwind borders would be the most enticing for pollution facilities.

But decisions about where to locate plants will, of course, also is affected by market demand, labor supply and natural resources, among other factors. So Monogan and colleagues compared the location of air polluters to a “control group,” the sites of 20,761 hazardous waste facilities, such as landfills. The logic? “The factors … that are potentially important in site selection of major air polluters also apply to the siting of hazardous waste facilities,” they write. “However, unlike major air polluters, there is no strong reason to locate a hazardous waste site either upwind or downwind. The pollution from these sites is contained (assuming they are compliant with relevant statutes) and not subject to the dispersion through airsheds.”

If air polluters are more heavily clustered along downwind borders than hazardous waste sites, then that suggests that their location reflects an attempt to send emissions out of state, not some other factor correlated with being near a downwind border.

And indeed, Monogan and his co-authors found that the farther a location is from a downwind border, the lower the odds that it will host an air polluter. For instance, being about 100 miles upwind of a state line reduces the odds of an air polluter locating there (compared to a hazardous waste facility) by around 6 percent.

The effect is also strongest among the biggest polluters. The facilities that release the most toxic emissions (measured by number of pounds) are the most likely to locate near a downwind border.

So what’s leading polluters to make these decisions? The authors acknowledge that their data can’t say anything about the process that brings pollution facilities to downwind borders. But they suggest two possibilities.

One is that state policy makers encourage it. For instance, Texas would surely want the economic development and tax revenue that would come from a new manufacturing plant. But the state could probably do without the resulting toxic emissions. So one option would be to encourage a manufacturer to locate on Texas’ northern border, where the wind tends to blow across the Red River into Oklahoma.

Alternatively, companies might decide on their own to build a facility in a location where pollution would be carried across state lines. Doing so might reduce the effectiveness of NIMBY, or not-in-my-backyard, activism. If the citizens who feel threatened by a plant live across the border, they may have a hard time persuading lawmakers in the facility’s state – who have little incentive to attend to the concerns of out-of-state residents – to oppose its construction or operation.

Regardless of how polluters come to live along the border, Monogan, Konisky and Woods conclude by noting one of the profound challenges of federalism. With states and businesses constantly making environmental decisions that have cross-border consequences, a decentralized regulatory system may confound pollution control efforts. And if you live in Ardmore, Okla., that tickle in your throat might have ridden the breeze blowing up from the Texas border.