CHICAGO (CBS) — Her nose keeps us safer as we travel, and now she’s heading for a well-deserved retirement.

Lacy, a certified passenger screening canine for the TSA, is retiring after seven years on the job.

Lacy and her handler, Diana, were part of the first-ever graduating class of TSA screening dogs at Auburn University in 2011. A black lab, Lacy is specially trained to sniff out explosives.

“It’s been fun, and also challenging at the same time,” Diana said. “It was a new path for us, so we were paving the way for a new endeavor for TSA”

The TSA estimated she has screened more than 1 million passengers at Midway and O’Hare airports.

“We have a routine, and we try to do many different things throughout the day, It’s busy. We don’t sit down much,” Diana said. “I hope we’re making a difference. That’s the important thing, that we are making a difference.”

She is on hand at Midway on Tuesday, sniffing out her final shift.

Now that Lacy is retiring, she’ll be living at home with Diana and her kids, and getting plenty of walks.

“I do want to keep her fit the way she is now, so that she can live a long life,” she said. “She enjoys being on a treadmill. That’s something that she picked up from Auburn that I continued at home, and she will continue through her retirement.”

Because of her specialized training, and the reward system required to do her job, Lacy hasn’t socialized much with anyone but Diana the last seven years.

“She couldn’t just be like a regular dog, playing with any toy that she wanted,” Diana said. “Now she can play with the kids, and have all the toys that she wants, and play at home. So it’ll be a different type of retirement and environment at home.”

Diana said Lacy might get a little jealous of her now, since Diana will be working with a new dog at O’Hare and Midway.