The TSA announced earlier this month they would begin removing the 174 controversial body-scanning machines that populate 30 airports nationwide, according to the New York Times.

The machines have been under scrutiny since the Transportation Security Administration began placing them in airports in 2010, after a failed attempt by self-proclaimed terrorist, Umar Farouk Abdulmutallab, to blow up a Northwest Airlines flight by setting off explosives he had hidden in his underwear.

Those opposed to the use of the machines include both health and privacy advocates.

 Health advocate’s concerns about the machines centered on the machine’s use of X-Ray technology, which exposes travelers to a small dose of radiation, according to Wired Magazine.

Though the TSA maintains that the machines are safe for travelers, they recently commissioned the private non-profit organization, the National Academy of Sciences, to study and estimate the radiation exposure from the machines, said CNN.

Privacy groups oppose the use of the body-scanning machines, which are made by Rapiscan, because of the graphic image the machines produce for security officers to examine. The image essentially shows the person being scanned naked, which privacy advocates argue is needlessly invasive, according to the Times.

It was the privacy concern that ultimately ended the government’s use of the Rapiscan body scanner in favor of a new scanner, made by L-3 Communications, which creates a cartoonish outline of the human body, according to the Times. Rapiscan will pay for the removal of their machines from airports.

The new body scanners, which will replace all Rapiscan scanners by June 2013, also alleviate health advocate concerns, as they do not use X-Ray technology. Instead, they use millimeter waves, according to CNN.

In addition, the new machines should speed up lines at airports, as they work more quickly than their Rapiscan counterparts, according to the TSA.

One drawback of the new millimeter machines is that they tend to have a high false-alarm rate, according to tests conducted in Europe and Australia.  Things such as folds in clothing and sweat have triggered false alarms in these machines, according to Pro-Publica.

The false alarm rate in the Rapiscan machines was around 5%, according to officials in a Manchester airport, said Pro-Publica.

Interested in seeing the difference between the Rapiscan machine and the new L-3 machines? Check it out on this Pro-Publica page: http://www.propublica.org/special/scanning-the-scanners-a-side-by-side-comparison