The vast majority of those traveling today who could be subject to full-body scans at U.S. airports are not refusing those scans, despite an online call for a "National Opt Out Day" on the eve of Thanksgiving, according to an "unofficial" review of airport operations by a government official.

At New York's LaGuardia Airport and Boston's Logan International Airport, there have been "very few opt outs" so far, according to the official. At Baltimore Washington International airport, four passengers "opted out." Those were the only "opt outs" reported as of 10 o'clock Wednesday morning, the official said.

Critics of new security measures implemented by the Transportation Security Administration call on those traveling today - one of the busiest travel days of the year -- to refuse full-body imaging, which forces TSA agents across the country to give pat-downs and, critics say, would let Americans "see for themselves how the TSA treats law-abiding citizens."

"The government should not have the ability to virtually strip search anyone it wants without cause," says the website OptOutDay.com. "We do not believe the government has a right to see you naked or aggressively touch you just because you bought an airline ticket."

Other sites, such as WeWontFly.com, went even further.

"TSA does not have the manpower to stick their hands in the pants of everyone coming through there," said the site's co-founder, James Babb. "We are encouraging people to not just opt out of the radiation scan but also opt out of the groping by not flying at all."

Wednesday morning, TSA Administrator John Pistole told Fox News that if "a number of people" decide to "opt out," such a move would "slow down security check points" and "would have the possible unavoidable consequence of people missing flights."

But, as of 10 a.m., transportation security officials across the country are reporting relatively short lines at security checkpoints and positive feedback from passengers.

At Minneapolis-St. Paul International airport, the wait to go through security is about 10 minutes, and security officers have received "lots of passenger compliments," the government official said. Similarly, at the airports in Manchester, N.H., and Harrisburg, Penn., the wait to go through security is less than five minutes, and "passenger feedback" has been "very positive" and "very supportive," the official said. In Richmond, Va., no passengers at the airport there have "opted out," and security officers are receiving "lots of thank yous," according to the official. Other airports report similar situations.

The official in charge of security at the airport in Burlington, Vt., told government officials that one passenger commented after receiving a pat-down, "That's it? That's all there is to it? ... I've received more invasive pat-downs just going to a rock concert." Other recent travelers, though, have described the pat-downs as too invasive.

In fact, according to recent polls, Americans are split over whether the pat-downs experienced by those who "opt out" go too far. However, fewer than three percent of travelers receive pat-downs, according to the TSA.

As for the full-body scanners, the vast majority of Americans -- as much as 80 percent -- approve of their use at U.S. airports, according to recent polls.

Only 68 airports around the country currently have body scanners. There are 385 units at those airports, and TSA plans to deploy hundreds more across the country in the next two years. According to TSA and DHS, an officer located away from the security line views a slightly blurred, X-ray-like image of a passenger, but the officer does not see the passenger. The image cannot be stored, transmitted or printed, and is deleted immediately once viewed, authorities have said.

On Tuesday, Homeland Security Secretary Janet Napolitano sent an email to all TSA employees, saying she wanted to "take a moment to personally thank you for the work you are doing to keep the traveling public safe."

"The threats we face in the aviation sector are real and evolving, and we are meeting them with a strong and dynamic response," she said. "Serving on the front lines, you ensure safe and efficient travel for the millions of people who rely on our aviation system every day."

In her email, Napolitano insisted that "time and again, the men and women of TSA have demonstrated poise and professionalism.""Travelers and the public realize that your job is difficult and demanding," she said. "This holiday season, I am confident you will again demonstrate your commitment to ensuring the safety of the traveling public to everyone who passes through an airport security checkpoint."

She said that as the threats against the United States "continue to evolve, the nation continues to count on you as their last line of defense against terrorism and rely upon you to execute your mission efficiently, professionally and courteously."Nevertheless, several websites are calling for a national "Opt Out Day," insisting many Americans "only fly around the holidays and may not be aware of the security changes."

"The government should not have the ability to virtually strip search anyone it wants without cause," says the website OptOutDay.com. "We do not believe the government has a right to see you naked or aggressively touch you just because you bought an airline ticket. ... Once people are made aware of what is happening, they may have reservations about the new virtual strip searches and enhanced pat downs -- especially for their children or spouse or other loved one."

During a press conference last week, Napolitano said she "really regrets" such calls to "opt out" of certain screenings, adding that TSA and her department act responsibly "with good intelligence, with risk-based analysis."

She said "everybody has a role to play" in preventing terrorism "and if people don't want to play that role, if they want to travel by some other means, of course that's their right."

On Tuesday, Pistole called the calls for a "National Opt Out Day" simply "irresponsible."

"On the eve of a major national holiday and less than one year after Al Qaeda's failed attack last Christmas Day, it is irresponsible for a group to suggest travelers opt out of the very screening that could prevent an attack using non-metallic explosives," Pistole said in a statement. "This technology is not only safe, it's vital to aviation security and a critical measure to thwart potential terrorist attacks."