Ottawa has announced plans to equip 11 Canadian airports with scanners that can see through the clothing of air travellers, allowing security personnel to root out potential airline terror threats.

Transport Minister John Baird and Minister of State Rob Merrifield held a press conference Tuesday afternoon, saying the government will install the machines within the next two months.

Merrifield said the government would purchase 44 units that use millimeter wave imaging technology, at a cost of roughly $250,000 per unit, which includes parts and staff training. Eleven of the scanners are to be installed next week, he said.

"We are not immune to acts of terrorism or terrorist threats," Merrifield said. "We must therefore continue to be at the forefront of new security technology."

Merrifield also noted:

  • Individuals will only go through the scanner if they are singled out for extra screening, and will have a choice of whether they prefer a pat-down search.
  • Images will not be stored, printed or transmitted. They will be deleted after they are viewed.

Baird said that the new security precaution will not apply to anyone under the age of 18, so minors will not be sent through the body scanners.

However, for travellers who show extremely suspicious behaviour, the body scanners will be mandatory.

Montreal's La Presse newspaper reported Tuesday that Montreal, Toronto, Ottawa, Halifax, Vancouver, Calgary and Edmonton will be among the airports to have the new scanners installed.

As a result of new security requirements implemented by Washington, Baird said the Canadian government "will continue to implement additional security measures and increase screening for flights going to the United States."

He added that the new machines would hopefully reduce lineups and waiting times for air travel.

"It won't be easy but we're committed to doing all that we can to ensure that these new security measures will be done as expeditiously as possible, with minimal delays to Canadians," Baird said.

The Canadian Air Transport Security Authority says the low-level radio frequency wave emitted by the body scanner meets Canadian health-and-safety standards.

The devices have already been tested at an airport in Kelowna, B.C., and enable a screening officer to see if someone is carrying explosives or other dangerous items. The machines are considered to be controversial, however, because they produce a three-dimensional outline of a person's naked body.

Additionally, the system was approved by Canada's federal privacy czar last October, under a plan that would see officers viewing the images in a separate room, so that they never saw the actual air traveler.

Such scanners are currently used at airports in cities including Amsterdam, Moscow and Phoenix. They are also used in Baghdad's security "green zone" and in some U.S. courthouses and prisons.

Canadian officials had not previously signalled an intention to rush the scanners into service.

But in the wake of the botched Christmas Day attack that saw an alleged Nigerian terrorist attempt to destroy a Detroit-bound U.S. airliner, Ottawa decided to purchase the scanners despite the multimillion-dollar price tag.

Former CSIS intelligence officer Michel Juneau-Katsuya said the new scanners will be "very, very expensive" to buy and to hire additional personnel to operate them.

He described the technology as "like sonar."

"It sends a wave and gives you a silhouette of the person. Anything unusual will immediately appear on the screen and can be detected."

But is it safe?

Since 2007, the U.S. Transport Safety Authority has been testing out new imaging technologies, as a way to detect "a wide range of threats to transportation security in a matter of seconds," the agency's website says.

Under the program, the TSA set up 40 millimeter wave imaging scanners at 19 American airports, including six airports where the machines are used for primary, rather than random scans.

The machines create a three-dimensional image of an air traveller by beaming a radio wave at them from two rotating antennae, creating an image "that resembles a fuzzy photo negative" of the person's body.

The TSA says the amount of energy the antennae project is about 10,000 times less than that from a cellphone call.

"We, and all objects around us, generate millimeter wave energy-- and we are exposed to it every single day," the agency says.

The person's face is blurred out on the scanned image as a privacy measure. As with the proposed Canadian system, operators in the TSA's pilot program view the images from a remote location so they can't see those who are being scanned in person.

At least one company has commercialized the technology for purposes other than security -- to take measurements for making or purchasing clothes.

A scanner developed by an American firm called Intellifit uses low-power radio waves to take precise body measurements so that users can "shop online for custom-made clothes" and "be matched to 'guaranteed-fit' sizes of brand name apparel," the company's website says.

Intellifit estimates its scanner uses a radio wave that's about 1/350th of a cell phone signal.

With files from The Canadian Press