The next time you go to the airport you might notice something different as part of the security process: A machine scanning your face to verify your identity.

U.S. Customs and Border Protection (CBP) has been working with airlines to implement biometric face scanners in domestic airports to better streamline security. In fact, they're already in place in certain airports around the country.

But how does the process work? Which airlines and airports are involved right now? And do travelers need to be concerned about privacy breaches?

Here's everything you need to know about the latest technological advances in airport screenings, from the government's work to privacy concerns and more.

What is biometric airport screening?

It's a fancy way of saying that the government is using facial recognition technology at the airport. Government agencies (in conjunction with airlines) are aiming to improve efficiency when it comes the way travelers enter and exit the U.S.

This is separate from the eye and fingertip scanning done by CLEAR, a secure identity company available at more than 60 airports, stadiums and other venues around the country. (CLEAR is certified by the Department of Homeland Security).

Here's how the process of facial scanning at the airports works: Cameras take your photo, and then the CBP's Traveler Verification Service matches it to a photo the Department of Homeland Security has of you already. These could be images from sources like your passport or other travel documents.

This process will ideally replace the manual checking of passports nationwide.

Where did this idea come from?

"A form of biometric entry-exit was technically required for non-U.S. citizens by the Illegal Immigration Reform and Immigrant Responsibility Act, which was signed into law in 1996," says Jeramie Scott, senior counsel at the research firm Electronic Privacy Information Center (EPIC) and director of the EPIC Domestic Surveillance Project. Scott notes, however, the years-old requirement wasn't fully implemented.

After 9/11, a commission recommended a full implementation of the biometric entry-exit scanning, but it wasn't until 2017 that President Donald Trump signed an executive order that expedited the full roll out.

The CBP explained in a statement to USA TODAY U.S. citizens have historically been processed at border check points in-person but the facial recognition technology is being used because it "can do so with greater consistency and accuracy."

"CBP is simply replacing the current manual travel document comparison with facial comparison technology," the agency stated.

Facial recognition became the government's method of choice – as opposed to finger print or other scanning – because it already had people's photos in most instances, Scott explained.

In order to quickly verify travelers' identities, photo galleries are pre-built from flight manifests so once a face is scanned it can be checked against the stored photo of a passenger.

CBP stores the photos of U.S. citizens scanned for no more than 12 hours post-verification, after which they are deleted.

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What are airlines doing?

With the exception of Southwest, most major airlines in the U.S. are taking steps to include the CBP facial recognition technology as part of their security processes.

Delta Air Lines

Toward the end of last year, Delta announced one of its terminals in Atlanta's airport was the "first biometric terminal" in the country. As of Dec. 1, all Delta passengers traveling internationally are able to take advantage of the biometric options when departing from the airport’s Terminal F. Delta has since expanded its facial recognition boarding practices to another Atlanta terminal as well as at airports in Detroit, Minneapolis and Salt Lake City. It also has a CLEAR partnership.

The face recognition technology replaces the traditional boarding method of showing your passport and ticket, according to Delta spokesperson Kathryn Steele. Passengers board after standing in front of a face scanner verifying their identities. A video of the system can be seen here. "This technology makes moving through the airport easier and is a part of our effort to create a seamless travel experience," Steele told USA TODAY.

Customers still need their passports and should take it with them for use at other touch points internationally, per Steele.

United Airlines

United has been testing facial recognition tech during boarding at some gates for international travel in Houston, Washington Dulles and San Francisco, United spokesperson Maddie King told USA TODAY. "When we do offer these tests they are always optional, and customers are always able to use their boarding pass and passport instead if they choose."

The airline is also working with CLEAR to further implement the biometric security option across its hub airports.

American Airlines

American has a pilot underway at Los Angeles' LAX Terminal 4, where passengers' faces will be scanned to verify identities in lieu of scanning boarding passes. The pilot has no end date, American spokesman Ross Feinstein confirmed to USA TODAY.

JetBlue Airways

Self-boarding is available on international flights leaving from New York-JFK, Boston and Fort Lauderdale, Julianna Bryan, spokesperson for JetBlue, told USA TODAY.

"Additionally, last fall, JetBlue became the first airline to partner with the Metropolitan Washington Airports Authority to launch a one-step biometric boarding experience for customers flying to Nassau, Bahamas (NAS) from Ronald Reagan Washington National Airport (DCA)."

The airline has fully implemented the tech on certain routes: "The flights from BOS-AUA and BOS-SDQ were considered 'pilots.' The trial ran from June 2017 to mid-2018. Since then, we have truly refined the technology, distancing the process from being a 'pilot' to having it become an essential part of our daily operations."

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Is the TSA involved too?

Yes. The agency is working with CBP as part of the security checkpoint pilot program in Atlanta's Terminal F, and is also working with Delta Air Lines to use biometric identification at the airline's bag drop. The TSA is evaluating the pilot's applicability for use elsewhere.

Austin Gould, the assistant administrator for requirements and capability analysis at TSA, told USA TODAY that more than 90% of people at the are opting into the program though always have the option to opt out.

"You need to knowingly step in front of the camera and agree to use your image as your identification in the pilot that we’re running," he says.

In the future, the TSA hopes to expand the program, including for TSA PreCheck passengers as well as for use during domestic travel. You can look at TSA's plans here.

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Can I opt out of the facial recognition program?

Yes. That said: "Even if you opt out of the facial recognition at the airport, your photo is still part of that gallery they created prior to the flight," Scott says.

The CBP clarified in a statement: "The biometric entry/exit program is not a surveillance program, CBP does not biometrically track U.S. citizens. Facial biometric processing at ports of entry only replaces current manual comparison using the travel document."

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Should I still be concerned about privacy?

It depends who you ask.

Both the CBP and TSA have conducted thorough privacy impact assessments related to facial recognition technology, though concerns loom among privacy advocates.

By consenting to the facial recognition, the government can create a digital identity for you and track you without your consent or knowledge, Scott adds. While they may not be using that power right now, there's a lack of regulation preventing them from using it that way. A small way of pushing back is to emphasize your right to opt out.

The American Civil Liberties Union is against the CBP's facial recognition program, according to Jay Stanley, a senior policy analyst with the organization's speech, privacy and technology project.

"The concern is that your face will be used to track and monitor you everywhere you go," he told USA TODAY.

Is the facial recognition program working?

For the CBP's part, facial recognition is already proving successful in terms of stopping people entering the U.S. illegally. "Since initiating this facial comparison technology in the air environment on a trial basis, CBP has already identified seven imposters, including two with genuine U.S. travel documents (passport or passport card), who were using another person’s valid travel documents as a basis for seeking entry to the United States," according to the CBP.

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