Airbnbs are booming as summer tourist season takes off in vacation hot spots like Cape Cod — as well as in residential neighborhoods. A new study from Northeastern University caused concern by showing a link between the number of Airbnbs in Boston neighborhoods and spikes in violent crime. To discuss the study, Dan O'Brien, director of the Boston Area Research Initiative and associate professor of public policy and urban affairs, and Babak Heydari, associate professor of engineering, joined Mary Blake on Morning Edition.

The study, which examined data from almost a decade, crossed Airbnb data with crime data from 911 calls. O’Brien said researchers were aware of the popular assumption that Airbnbs bring tourists, driving up crime. But researchers debunked that claim.

Instead, the study tested a second hypothesis, which their data indicates is correct: rather than the volume of tourists, the number of buildings that has a listing predicts an increase in crime.

“Our idea was that Airbnb is actually the most transient possible kind of household,” O’Brien said. “Essentially, those listings are poking holes in the social fabric.”

The hypothesis was rooted in criminology: the idea that as households become more transient, neighborhoods are not able to manage crime naturally, and people don’t follow local norms that would discourage bad behavior.

The disruption caused by Airbnbs forces “contributing households” out of the neighborhood, O’Brien said, noting that the highest rates of Airbnbs in Boston are in neighborhoods like Allston, Brighton and the South End — with less penetration in neighborhoods with lower access to public transportation.

Of the three types of crime that the study examined — public social disorder, public violence and private conflicts — researchers saw the most significant increase in public violence in Boston, Heydari noted.

“We did not see any significant effect of Airbnb on increase in public social disorder, which, incidentally, is the category of crime that we usually hear in the news and in the anecdotes that people use for describing the effect of Airbnbs on criminal activities in neighborhoods,” he said.

O’Brien said he hopes the study will generate a push to change laws around Airbnb. The original policy was created by city councilor and mayoral candidate Michelle Wu, and requires that each Airbnb be in a building that is owner-occupied, to discourage them from becoming clusters, essentially “hotels.”

"Those listings are poking holes in the social fabric."
-Dan O'Brien, Northeastern University

“It was really thoughtful. And it has a good approach, but it does have some vulnerabilities. It is focused on oversight,” O’Brien said. “But it doesn't address this broader neighborhood challenge that could potentially arise. If you imagine a neighborhood that's composed entirely of two and three family homes or triple deckers, which is not hard to imagine in Boston, you could technically have an Airbnb listing in every building.”

Airbnb has released a statement refuting the study and its methodology.

“All the comments they [Airbnb] have raised are already clearly addressed in our paper,” Heydari said, defending the takeaway of his study. “We also identify a reason, the causal mechanism for the effect we're observing, that is related to the increase in the crime rate to erosion of social organization, which is in part is caused by the presence of short-term rentals.”