Assessment of the current situation by AFA-International ASHS OSHA Specialist and Certified Industrial Hygienist (CIH), Dinkar Mokadam:

My conclusion regarding this update is that it represents an accurate assessment of the current situation with respect to radiation levels in the areas surrounding the Tokyo metropolitan airports, and concurs with the dosimeter readings we have collected over the past two weeks. Our readings show undetectable or nearly undetectable levels of background "excess" radiation in the Tokyo area during the period of the recent crisis involving the accident(s) at the Fukushima No. 1 Nuclear Power Plant.

Provide Flight Attendants with additional resources, as well as an explanation of the information found on the Japanese site in layman’s terms; as well as providing an high overview (confirmation) of the data we are receiving from the Dosimeter’s that AFA has deployed to all our carriers who fly to Japan.

Some more detailed comments regarding the Japanese government data and our measurements are below:

On the downloaded Japanese government PDF, typical dose rates are highlighted in the red box.  These levels may be compared to the Recommended Limits reported by the FAA in Section7 of AC 120-61A, PDF also attached.  Specifically, 7.b of the AC states the following:
The recommended occupational exposure limit for ionizing radiation is a 5-year average effective dose of 20 millisieverts per year, with no more than 50 millisieverts in a single year.

For a pregnant crewmember, the recommended limit for the conceptus is an equivalent dose of 1 millisievert, with no more than 0.5 millisievert in any month.

As an example: For a NY-Tokyo-NY roundtrip with a 0.2 mSv cumulative dose, it would take 100 trips / year to reach the recommended annual dose.  As of 4/11/11, the maximum dose obtained from any single flight, 9 mrem (which is equal to 0.09 mSv, since 1 mSv = 100 mrem), was recorded on a trip from IAD to NRT.  This is agrees well with the FAA and Japanese government data.

Data confirmation:  With respect to exposures on layovers, so far, only one of the doses measured while on the ground in Tokyo has been above the 2 mrem (0.02 mSv) level that is reportable by these dosimeters. This was a 3 mrem dose recorded on device # 24785, which is one of the NRT base dosimeters, accumulated between 3/28 and 4/1 (based on US Eastern time zone).