Over the coming weeks, AT&T is rolling out cellphone location tracking that’s designed to route emergency calls to 911 more quickly. The company says the new feature will be nationwide by the end of June and should make it easier for, say, an ambulance to reach someone experiencing a medical emergency. At first glance, it seems like a no-brainer. But it’s also a reminder that as phone companies promise to save lives, they’re also using a lot more data about you in the process.

The AT&T upgrade is part of a broader effort to modernize the country’s approach to emergency response. T-Mobile has also started using location-based routing, and experts told Recode that the technology could eventually be universal. At the same time, the federal government is in the midst of a nationwide push to get 911 call centers to adopt a technology called Next Generation 911, which will allow people not only to call 911 but also to send texts including images and video messages — to the emergency line.

Meanwhile, Apple and Google have created new software that can directly pass on information from someone’s device, like information stored on a health app. The hope is that more data will save crucial time during emergencies, but privacy experts are already warning that the same technology could be misused or exploited.

“I just worry what happens the next time there’s a tragedy, the next time people are scared, and the next time there’s an opportunity to use this data in ways it was never intended,” Albert Fox Cahn, the executive director of the Surveillance Technology Oversight Project (STOP), told Recode.

One of the main ways phone networks plan to use this data is to connect callers with the right 911 operator more quickly. Because the 911 system was designed to work with landlines, calls to 911 made via cellphones (mobile phones place the majority of 911 calls) sometimes get routed to the wrong 911 center. In places that use older technology, cellphones will generally connect to the 911 operator associated with the antenna on the cell tower that processes the call, not the 911 operator in the jurisdiction the person calling is currently in. When these calls are misdirected, it can sometimes take several minutes to be connected to the right dispatcher.

To address this problem, carriers are turning to the sensors in smartphones, like GPS, wifi antennas, accelerometers, and pressure sensors. Depending on the phone you have, either Apple or Google can then use these sensors to estimate your current location. (Google’s system is called Emergency Location Service, or ELS, and Apple’s system is called Hybridized Emergency Location, or HELO.) With AT&T’s and T-Mobile’s new systems, when someone makes a call to 911, the phone network will use this location estimate to make a best guess as to where someone is, and then connect the call to the right 911 operator. AT&T says the whole process should take about five seconds and is supposed to locate someone’s call within 50 meters of their actual location.

This isn’t the only data 911 centers have at their disposal. Apple already allows people to load their medical information — like what health conditions they have and medications they’re on — into their devices, and depending on the technology used by the jurisdiction you’re in, that info could be automatically sent to emergency responders when they dial 911. Some Apple Watch models also have a built-in fall detector that can dial 911 on its own.

Meanwhile, the Federal Communications Commission (FCC) has ordered carriers to start transmitting vertical location data in addition to horizontal location data, making it easier for first responders to identify what floor someone might be on in a multistory building during an emergency. And as the federal government rolls out Next Generation 911, it’s also laying the groundwork for 911 operators to collect data from other connected devices, like cars with certain crash notification systems, building sensors, and wearables. This is all in addition to a host of other changes that a growing number of the country’s thousands of 911 call centers have been slowly making: upgrading software, sharing and collecting more analytics, and just getting better training. The idea behind all of these updates is that, with more information, dispatchers can make better decisions about an unfolding situation.

“A lot of the underlying efforts around transforming 911 is really trying to help the current nation’s 911 system, prioritize health and safety for call takers and dispatchers, and really just trying to ensure that the right person is being dispatched at the right time,” explains Tiffany Russell, the mental health and justice partnerships project director at the Pew Charitable Trusts. “This police-first model is not necessarily the best response to handle these really complex problems or issues related to mental health.”

In an emergency, more information could be helpful, but there are also reasons to worry about 911 collecting additional data. Allowing 911 operators to receive image- and video-based messages could create new opportunities for racial bias, Russell points out, and texting may not be the most efficient way for an operator to communicate during an emergency. The 911 system has played a fundamental role in and contributed to some of American policing’s worst problems, including over-policing, racist police violence, and deeply flawed approaches to domestic violence and behavioral health.

Another growing concern is data privacy. While AT&T told Recode that location data is only used when a 911 call is in progress, there are circumstances where 911 operators can directly request that information from a carrier, even if the person who made the call has hung up, according to Brandon Abley, the director of technology at the National Emergency Number Association. There is no way for an individual user to disable the location information sent during 911 calls.

These concerns with the 911 system aren’t new. When the FCC rolled out enhanced 911 — an early program to improve the kind of information 911 operators receive about wireless callers — civil liberties organizations like the Electronic Frontier Foundation (EFF) warned about the risk that federal agencies could try to access the data created by the new technology, or it could end up in the wrong hands. A recent FBI guide to cellular data shows that law enforcement does sometimes try to collect data created by carriers’ enhanced 911 capabilities. It’s also abundantly clear that cellphone location data generally isn’t well protected. Agencies like the FBI and the Department of Homeland Security have bought app-created location data on the open market, and as long as they have the right legal paperwork, law enforcement can reach out to any company that collects data about someone and ask for information.

“They are not responsible with our data, there are not proper assurances in the law to limit how they use it,” Andrés Arrieta, the director of consumer privacy engineering at EFF, told Recode. “Sometimes even when there are, they keep misusing it.”

These risks stand to get a lot more serious — and a lot murkier — as 911 centers across the country start receiving far more data from people’s devices. This could take some time, since 911 call centers are generally run on the local level and vary considerably in terms of the technology they use. Still, it’s critical to remember that even if a new service is designed or marketed as a new way to save lives, there’s no guarantee that’s the only way it will be deployed.

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