Joe Miller knew that airport security measures were changing before he arrived at Atlanta Hartsfield-Jackson International Airport en route to Louisiana. But he didn't feel the full effect until he declined to go through a full-body scanner and ended up in a private room with an airport security worker touching his genitals.

"I know it sounds extreme, but if someone had done that to me in public, I would have been screaming and hollering for police to help," said Miller, of Sandy Springs.

Miller is among the millions of Americans who are experiencing new and very personal airport security measures as they travel this year. The measures, which include full-body scans that produce highly accurate three-dimensional body images, as well as "enhanced" pat-downs instituted last month, are igniting a backlash over privacy.

On Monday U.S. Secretary of Homeland Security Janet Napolitano defended the use of full-body scanners, which she said will become a routine security procedure as hundreds are installed in U.S. airports.

"It's all about security," Napolitano said. "It's all about everybody recognizing their role."

Several people interviewed at Atlanta's airport said they welcomed the more stringent security measures.

Kellie Meritt, of Clayton County, a travel consultant who travels twice a month, said that although she was concerned that the image from the machine might find its way onto the Internet,  she feels the new measures can provide greater protection.

“I’d rather be patted down than blown up,” she said.

At present, most airports, including Hartsfield-Jackson, are using a combination of metal detectors and the new scanners. Which device a passenger goes through is a matter of chance.

If either the metal detector or the body scanner detects something suspicious, or if the passenger refuses the body scan, a TSA worker of the same gender will perform a full body pat-down. The passenger may request that the pat-down be done in a private room with a second TSA worker present to guard against inappropriate touching.

Some passenger groups are planning to boycott the full body scanners on the day before Thanksgiving, known as the busiest travel day of the year. The tactic is designed to force TSA workers to perform a pat-down in front of other passengers, drawing attention to the practice and encouraging people to complain to their lawmakers.

Writes National Opt-Out organizer Brian Sodegren on his website: "We do not believe the government has a right to see you naked or aggressively touch you just because you bought an airline ticket."

However, Keo Buford, 33-year-old Fairburn resident, said he didn’t mind when he was patted down while embarking to Miami Friday. As for those raising objections, he said, “It’s a little selfish, all that kind of foolishness.”

The backlash represents a shift in public sentiment from the days following 9/11, when security measures were extremely high and many people accepted them. The TSA and those who support the new measures point out that they are designed to foil terrorists who attempt to bring down aircraft with plastic explosives not detectable by conventional metal detectors.

The TSA has stepped up efforts to put the new scanners in place since several well-publicized incidents involving the explosive PETN, including the so-called "underwear bomber" apprehended on a flight from Amsterdam to Detroit last Christmas day.

Constitutional attorney John Whitehead, president of the Rutherford Institute, a civil liberties organization, said the searches violate the Fourth Amendment. He's currently representing pilots who refused the scans and pat-downs and were not allowed to fly.

"We’ve never had full body pat-downs or strip searches in American unless there’s reasonable suspicion the person you are searching is involved in criminal activity," he said. "What's the next thing? Body cavity searches?"

TSA spokesman Jon Allen would not specify what areas are approved for pat-down examination, citing security concerns, but widespread stories and Internet videos report people who have been touched on their breasts, genitals and inside their waistbands.

Whitehead said he's heard from hundreds of angry passengers, including the father of a 12-year-old girl who cried as she was inspected by a security worker. The TSA does permits pat-down searches of children 12 and older.

Using full body scanners to inspect passengers also raises health and safety concerns.

Wendy Brant, 35, of Portland, Maine, refuses full body scans because of fears about radiation from some machines.

“I’m concerned about how it is affecting us,” said Brant, who sometimes travels to Atlanta. “I wonder how the machine is tested and calibrated, and what they do to make sure it is safe.”

Some full body scanners are backscatter machines, which utilize radiation. Atlanta's airport uses millimeter wave technology, bouncing electromagnetic waves -- not radiation --  off the human body to create a photo negative, TSA's Allen said. The energy emitted by millimeter wave technology is thousands of times less than what is permitted for a mobile phone, he said.

The federal Food and Drug Administration is among several scientific panels that have deemed the backscatter machines safe. FDA scientists estimate that a passenger would have to submit to 1,000 scans a year to exceed the standard for radiation exposure.

Physicists at Arizona State University, who performed an independent analysis of the radiation exposure involved in the airport scans, concluded that the dosage might be up to four times that calculated by machines’ manufacturer. Even so, they said, “the increased dose to individual passengers remains well below the doses that are known to cause adverse health effects.”

Peter Kant, executive vice president of Rapiscan, the maker of some of the backscatter machines now being implemented across the country, recently defended the safety of the company's Secure 1000 machines .

"In two minutes of a typical commercial airline flight, a person receives the same amount of radiation exposure that they would from one inspection by the Secure 1000," he said.

Martha Legare, of midtown Atlanta, said she views these measures as a violation of her privacy.

“It’s one more indicator of privacy being eroded on the basis of fear,” said the management consultant in her fifties, who travels three times a month. She’s been through the machine a few times, but hadn’t undergone the pat-down.

Ashley Roe, of Woodstock, underwent both a full-body scan and pat-down on a recent trip to Florida. She was unaware that TSA workers could see an image of her body during the scan, but said she understands the need for advanced security measures.

"I just wish TSA would provide more communication at the checkpoint," she said.