Looking at the Health Physics Society website, it seems that the International Commission on Radiological Protection (ICRP) and the FAA, recommend an occupational limit of 20 mSv per year. However, the limit for the travelling public is just 1 mSv per year. Not quite sure why we can take 20 times joe public's limit but there you go.
But based on 900 hours flying a year, we can take an average of 22 uSv per hour using the occupational limit. It all boils down to which limit do you trust?
Incidentally the limit during pregnancy appears to be 0.5 mSv per month, up to a max of 2 mSv over the full term of the pregnancy. This means you can take an average of 6.6 uSv per hour max, and you can only keep it up for 4 months then you have used up your quota. If you average above 6.6 uSv during your first month of pregnancy, your baby is at risk, so it seems you need to stop as soon as you are aware you are pregnant, if you suspect your dosage is above this.
Last edited by GS-Alpha; 22nd Jan 2005 at 17:53.