On 27/03/2011 15:39, Bernard Peek wrote:
On 27/03/11 15:49, Dave Liquorice wrote:
On Sun, 27 Mar 2011 14:06:43 +0100, Bernard Peek wrote:

One sievert is where people start to die.

In what timescales for both exposure and death?

One Sievert is the point where there is a significant risk of
radiation-poisoning rather than cancer. It's not necessary a death
sentence.

One Sievert over what time period? 1hr, a day, a year?

0.114 mSv/hr for a year is the same dose as 1 Sv/hr for one hour. The
latter may well have nasty consequencies, former probably not...

As far as I am aware the Sievert is intended to be a measure of the
damage caused by radiation, but the way dosage in Sieverts is calculated
does not distinguish between short and long-term exposures. It's quite
possible that a radiation dose received over an extended period may be
less harmful. Or not. Apparently nobody knows.

This might be a good place to start looking for some real answers.

http://en.wikipedia.org/wiki/Radiation_poisoning

A recent article that I read (I can't remember where) suggested that we
have used stright line graphs to assess the dangers of radiation doses,
but that our bodies have proved very able to self repair (probably as a
consequence of evolution dealing with natural background radiation) and
therefore the straight line has grossly overestimated the dangers of low
level exposure.

SteveW