Michael Grabell and Christian Salewski
December 19, 2011
While X-ray body scanners used in airports face concerns about potentially increasing cancer cases , a safer type of scanner has been plagued by another problem: a high rate of false alarms.
The scanner, known as the millimeter-wave machine, uses low-level electromagnetic waves that, unlike X-rays, have not been linked to cancer. The Transportation Security Administration already uses the millimeter-wave machine and says both types of scanners are highly effective at detecting explosives hidden under clothing.
But two of Europe’s largest countries, France and Germany, have decided to forgo the millimeter-wave scanners because of false alarms triggered by folds in clothing, buttons and even sweat.
In Germany, the false positive rate was 54 percent, meaning that every other person who went through the scanner had to undergo at least a limited pat-down that found nothing. Jan Korte, a German parliament member who focuses on homeland security, called the millimeter-wave scanner “a defective product.”
While it’s difficult to know for sure if the millimeter-wave machine has a worse false-alarm rate than the X-ray machine, recent tests suggests that it does. The TSA wouldn’t release its results, citing national security. But a British study found the X-ray machine had a false-alarm rate of just 5 percent.