Swine flu, body heat, and airport scanners.

Science, technology, and life.
April 28 2009 10:22 PM

Heat Check

Swine flu, body heat, and airport scanners.

A thermal scanner. Click image to expand.
A thermal scanner

Six years ago, when Severe Acute Respiratory Syndrome swept the world, governments bought thermal-image scanners and set them up at airports. The idea was to spot overheated travelers and check them for fever before they infected others. Now the machines are being deployed again, this time to catch swine flu.

William Saletan William Saletan

Will Saletan writes about politics, science, technology, and other stuff for Slate. He’s the author of Bearing Right.

The World Health Organization thinks this is folly. According to WHO officials, the virus has already spread too far, and anyway, "Fever monitoring doesn't work because you don't get the cases which are still in incubation." For these and other reasons, dozens of thermal imagers in Canada and Australia are sitting unused.

That's a shame. Heat scanners certainly can't handle the current flu threat by themselves. But they can help.


A recent report from the Canadian government explains how the devices work: They "determine the temperature of an object by measuring the amount of infrared radiation emitted by that object; the higher the temperature, the more infrared radiation that is emitted." You can watch scanners in operation here and here. To see what a machine operator sees, check out the photos here, here, here, and here.

Canada seems chastened by a four-year-old study that found its scanners weren't cost-effective against SARS. But most of the imagers now being deployed are already paid for. They were bought during the SARS and bird flu outbreaks. Why not use them?

It's true that the current flu has already spread to four continents. But that's no reason to suspend vigilance. Air travel is the fastest, most effective way to transmit a contagious human-to-human disease. At any given time, half a million passengers are in the air. From Mexico alone, weekly air traffic is more than 1 million people. Every interception slows transmission and buys time to catch up with drugs and vaccines.

In fact, one reason why scanners didn't do more to stop SARS is that they were deployed too late. In Canada, they took weeks to acquire and set up. This time, countries already have them on hand and know how to use them. We have a head start. And we're wasting it.

The scanners have their flaws. As the Canadian report notes, they "measure the skin and not the core temperature." But they don't have to be perfect. They just have to spot the people worth pulling over for closer inspection. If you're flagged, the next step is a thermometer check, an exam for symptoms, and an interview about your medical history and where you've been traveling. (In Indonesia, you might be "sprayed with a 70 percent alcohol solution.") If you test positive for influenza A, you might be quarantined at a hospital till you recover. But in that case, your itinerary is the least of your worries.



Don’t Worry, Obama Isn’t Sending U.S. Troops to Fight ISIS

But the next president might. 

IOS 8 Comes Out Today. Do Not Put It on Your iPhone 4S.

Why Greenland’s “Dark Snow” Should Worry You

How Much Should You Loathe NFL Commissioner Roger Goodell?

Here are the facts.

Amazon Is Launching a Serious Run at Apple and Samsung


Slim Pickings at the Network TV Bazaar

Three talented actresses in three terrible shows.


More Than Scottish Pride

Scotland’s referendum isn’t about nationalism. It’s about a system that failed, and a new generation looking to take a chance on itself. 

The Ungodly Horror of Having a Bug Crawl Into Your Ear and Scratch Away at Your Eardrum

We Could Fix Climate Change for Free. Now There’s Just One Thing Holding Us Back.

  News & Politics
Sept. 17 2014 7:03 PM Once Again, a Climate Policy Hearing Descends Into Absurdity
Business Insider
Sept. 17 2014 1:36 PM Nate Silver Versus Princeton Professor: Who Has the Right Models?
Sept. 17 2014 6:53 PM LGBTQ Luminaries Honored With MacArthur “Genius” Fellowships
  Double X
The XX Factor
Sept. 17 2014 6:14 PM Today in Gender Gaps: Biking
  Slate Plus
Slate Fare
Sept. 17 2014 9:37 AM Is Slate Too Liberal?  A members-only open thread.
Brow Beat
Sept. 17 2014 8:25 PM A New Song and Music Video From Angel Olsen, Indie’s Next Big Thing
Future Tense
Sept. 17 2014 9:00 PM Amazon Is Now a Gadget Company
  Health & Science
Sept. 17 2014 4:49 PM Schooling the Supreme Court on Rap Music Is it art or a true threat of violence?
Sports Nut
Sept. 17 2014 3:51 PM NFL Jerk Watch: Roger Goodell How much should you loathe the pro football commissioner?