Noise and motion monitors in their homes? These tenants say no.

Smoking is prohibited in public apartments. Excessive noise is frowned upon. Complaints from neighbors are the usual way to keep law-breaking residents in check, but New Hampshire’s public housing authority turned to technology to get the job done.

Residents who felt the government was spying on them in their homes were not happy about this.

In 2024, the Concord, NH, public housing authority began installing Minut sensors, a product popular with Airbnb hosts who want to ensure short-term guests don’t smoke or hold loud parties. About 300 affordable apartments in several buildings have the devices, which initially cost $50, with an additional $7.50 monthly monitoring fee.

“It is camera-free and does not record any sound or listen to what you say or do,” according to notices posted around the buildings.

But when some residents looked up Minut online, they were dismayed by the wide range of data the device collected: decibel levels, air quality and Bluetooth signals from mobile devices, a proxy for how many people were in the unit at any given time. The device even works as a motion detector.

Lisa Owens, an associate professor of law at the University of Massachusetts who has written about surveillance and public housing, said smart devices have become a “trend” since the Department of Housing and Urban Development banned smoking.

“You can see why this would not only cause a sense of unease among residents who are already at risk of falling through any safety net, but it could also have real privacy implications,” she said.

Tenants in Concord wondered what kinds of sounds set off the alarms. One tenant, whose Minut monitor was installed almost directly above her bed, wrapped it in plastic and put it in the freezer. Another asked her landlord—the government—why it was tracking her movements in her apartment and was incorrectly told the device didn’t collect that data. One mother asked her college son to hold him while playing video games in his bedroom just to be safe because the monitor was right outside his door.

No one wanted to lose access to low-income housing, but it didn’t seem fair that rental assistance meant living under constant surveillance, residents said. They contacted attorneys from New Hampshire Legal Assistance and the American Civil Liberties Union.

Lawyers sought more information about the monitoring through public records requests and received minute-by-minute data collected for each apartment. It involved hundreds of millions of sensor readings with thousands of data points about noise and movement in each apartment.

“I was amazed,” said Terri King, 65, whose Minut monitor was installed in January in the townhouse she shares with her husband. “I might as well open the door and let everyone in and see what I’m doing 24 hours a day.”

Mrs. King and her husband were fined $450 for repeatedly tampering with the device. She admits that her husband once removed the monitor to smoke, but does not know why the device reported other episodes of tampering. They received an eviction notice for non-payment of fines. The fine was later overturned after an attorney from New Hampshire Legal Assistance intervened.

On Wednesday, Ms. King and another resident sued the Concord Housing and Redevelopment Authority in state court. Since the agency is a state actor, the complaint calls the installation of the devices “a government intrusion into tenants’ personal and private information, as well as an ongoing warrantless government search of tenants’ homes.” The tenants are seeking class action certification on behalf of the other residents and want the devices removed from their apartments and the data collected about them deleted.

“The contract shouldn’t be: Have access to a roof over your head in exchange for complete oversight of your day-to-day activities,” said Nathan Wessler, an ACLU attorney representing the residents.

The Housing Authority did not respond to requests for comment.

Christopher Schott, one of the attorneys at New Hampshire Legal Assistance who also represents the tenants, said he is concerned that the data would be available to stalkers, employers or other interested parties through a public records request that would reveal when tenants were home or away or up late at night.

Minut, which is not being sued by tenants, says its technology is not intrusive.

“There is no camera or audio recording,” Nils Mattisson, Minut’s chief executive, said in an email. “Noise is measured as an average decibel level per minute. It’s just a number and can’t be used to determine what people are doing.”

Based in Sweden, Minut was founded in 2014 to offer a privacy-friendly solution for Airbnb hosts who wanted to monitor guest activity in their homes. In 2024 Airbnb forbidden indoor surveillance cameras and encouraged hosts to install noise monitoring devices like Minut’s instead – via Airbnb clarifies on their website that they should not be placed in bedrooms.

“Minut monitors adjacent to tenants’ beds may capture audio and motion data reflecting intimate interactions,” the tenants said in their complaint.

Mr. Mattisson said the vast majority of the company’s equipment was used in short-term rentals and that less than 5 percent of equipment sold was used in long-term housing.

“Public housing is different and completely new for us – we work with a handful of operators, mainly on cigarette smoke detection,” he said. “Most residents are good neighbors and the data is there to protect them.”

Aaron Krolik contributed reporting.