The United States has recently introduced millimeter wave and backscatter x-ray scanners to the security screening process in many airports, prompting a backlash in some quarters. Much of the opposition is centered around the invasion of privacy: the scanners generate an image of the traveller's naked body. There are also health concerns, at least for the backscatter x-ray variants of the scanners. I had initially dismissed these concerns as part of the usual overblown fears of anything related to radiation, but some scientists have recently raised concerns that while the radiation dose is low, unlike a medical x-ray or cosmic radiation, the entire dose is concentrated on the skin, intensifying the local dose by orders of magnitude. Personally, I agree with the that more study is warranted.
But are the scanners worth it, overall? Whether they are successful in deterring terrorists is one question that's been endlessly debated. But what about the effect of these security procedures on the economy? Nate Silver of the New York Times likens these security procedures as a "tax upon air travel":
Teleconferences are often a poor substitute for person-to-person interaction, and when people are reluctant to travel, some business deals don’t get done that otherwise would have. Recreational travelers, meanwhile, may skip out on vacations that otherwise would have brought them pleasure and stress-relief (while improving revenues for tourism-dependent economies). The tenuous profits of the airline industry are also affected, of course. Revenue losses from the new bag-checking procedures may have measured in the billions.
It certainly seems plausible that there is a quantifiable drain on the economy. But could we measure it? Nate suggests we could, via a statistical experiment.
If, for instance, Chicago O’Hare installs new machines and Chicago Midway does not, and passenger traffic at O’Hare drops by 9 percent while traffic at Midway holds steady, that would provide considerably more tangible evidence of how travelers are reacting to the new protocols than polls ever could.
It's a great idea. It's just a shame that political considerations would never allow it to be implemented.
New York Times: The Hidden Costs of Extra Airport Security