[DBrow]

I’m going to assume you know what the units are, so we’re on the same page.

From a post of mine on another thread:
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You can get as much as 660 micro-REMS per hour in flight, with 250 micro REMS per hour being a low average. That’s at least ten times ground level background.

If the xray scanners are harmful with their less-than-a-second less than 25 microrem scan, airline flight is many many times more dangerous.

http://www.hps.org/publicinformation/ate/faqs/commercialflights.html

Plus, lots of airline radiation is heavy particles and neutrons, not just low energy x-rays.
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So air flight gives you at least 200 uREM/hour. This memo:

http://www.whitehouse.gov/sites/default/files/microsites/ostp/fda-backscatter-response.pdf

says that the scanners are limited by law to 25 uREM per scan, and you’ll find actual measurements in the 5 uREM to 9 uREM from AS&E.

So you get more dose in flight. Plus, the in-flight dose is made up of higher energy photons mixed with particles from cosmic rays, and a bunch of really hot neutrons. Looking at the numbers, you can get more dose in an hour on a plane than you get from a scanner.

[bvw]

There are many forms of radiation, and many ways in which they damage cells. Moreover which cells get damaged is important, which cells, which organs. The concept and use of REMs is a dangerous oversimplification, imo. I never liked the concept.

In instant case: we have NO experience with the long term biological effect of back-scatter x-rays and also none with devices that use the terahertz radiation. What has been done to calibrate the REM so far is modeling or various sorts.

The REM dosages you read of during an airline flight are not x-rays, they are cosmic rays. The two things do different kinds of damage. In fact the body may be more able to repair the damage from cosmic rays than a REM equivalent of x-rays, or terahertz radiation.