The Infinite Brief

The technology behind the ads, known as geofencing, or placing a digital perimeter around a specific location, has been deployed by retailers for years to offer coupons and special offers to customers as they shop. Bringing it into health care spaces, however, is raising alarm among privacy experts.

“It’s really, I think, the closest thing an attorney can do to putting a digital kiosk inside of an emergency room,” says digital marketer Bill Kakis, who runs the Long Island, N.Y.-based firm Tell All Digital.

The advertisers identify someone’s location by grabbing what is known as “phone ID” from Wi-Fi, cell data or an app using GPS.

Once someone crosses the digital fence, Kakis says, the ads can show up for more than a month — and on multiple devices.