BOSTON -- It's a sign of the times: busy travelers conducting business on their cell phones and laptops.

We often see them hard at work, taking advantage of public Wi-Fi networks at airports around the country.

But according to one computer systems expert, those public networks may compromise the information you have on your laptop.

"Most of these networks are not encripted, don't have any special security built into them; everything they're typing into their laptop -- passwords, usernames -- is in the air," said Michael Maggio, chief executive officer of Newbury Networks.

Thursday, the Better Business Bureau in Eastern Massachusetts issued an alert. It warned travelers who use laptop computers that hackers have been setting up in and around airports fake Wi-Fi networks designed to steal personal files and information.

The Better Business Bureau said an investigation at busy O'Hare International Airport in Chicago revealed 20 such ad-hoc Wi-Fi networks attempting to steal information from travelers' computers.

Officials at Massachusetts Port Authority, which operates Logan Airport, said they have been alerted to the problem.

"Massport is aware of the current issue involving Wi-Fi scams at airports, and we're doing everything possible to prevent it from happening at Logan Airport," said spokesman Phil Orlandella.

Some travelers at Logan Airport Friday said they do all they can to try to make sure their information is not compromised.

"I've disabled my (wireless Internet) connection. That's why I'm not concerned," said Mark Swenson of Salt Lake City, Utah.

Robert Martinez, of Kansas City, Mo., was using his laptop computer as he sat on the floor at the United Airlines terminal at Logan.

Martinez said he is very cautious about when and where he will log on to a wireless network.

He uses his laptop, "basically from home or in a hotel, but not in an airport," he said.

Orlandella said his agency closely monitors the access points on the system.

"To date, there has been no reports of stolen data at Logan," he said.

Not all travelers are concerned that information communicated from their computers is of interest, or value, to others.

"I'm not a businessman; you see, I'm a scientist mostly. I do have some sensitive information, I suppose. But it's not particularly, I can't think of many people for whom it would be valuable," said Alex Groisman of San Diego.

Still, Maggio has a word of caution to anyone connects their personal or business computer to the Internet over a public Wi-Fi network.

"Don't do it if you don't have to," he said.