Radiation Protection

Any material between you and the
radiation source grants a Protection
Factor (PF) that reduces your received
dose. Divide your dose by PF; e.g., PF
100 means 1/100 the dose. Half an
inch of lead, 1.5 inches of steel, or 750
yards of air has PF 2; a yard of water
has PF 8; a yard of earth has PF 27;
and a yard of concrete has PF 64.
Shielding
protects
differently
against certain types of radiation.
Radiation from solar flares and plane-
tary radiation belts (like the Van Allen
belt) is mostly free electrons and alpha
particles: multiply PF by 20. Against
cosmic rays, divide PF by 100!