Re: How do we analyse radon in the lab without the use of a scanner?

    First, if you can expose a number of CR-39 strips to radon of known 
concentration (pCi/L or becquerel/m^3)for different known amounts of time, 
then you can plot the different [(pCi/L) x hours] against the number of 
etches you can count in a given area.  There should be a linear 
relationship in this plot.  That means that the data should plot along a 
straight line, with twice as many etches per mm^2 for a radon time 
concentration of twice the original [(pCi/L) x hours].
    As an example, 50 (pCi/L)*hr  may produce 10 etches per mm^2, and 100 
(pCi/L)*hr would produce 20 etches per mm^2, and 200 (pCi/L)*hr would 
produce 40 etches per mm^2.
    Then, with this information in hand, an unknown radon concentration 
can be calculated if the time of exposure is known and the number of 
etches per mm^2 can be counted.
    The CR-39 strips are usually placed in a small container with an 
opening covered with a particulate filter in order to eliminate the 
effects of different radon progeny concentrations.
    The company that supplies the CR-39 plastic may be able to provide you 
with information on how many etches per mm^2 should occur from exposure to 
a known time-concentration of radon.  If that information is not available 
from the company, then it will be necessary to create a known radon 
concentration for exposure of CR-39 plastic material.  This will allow you 
to calibrate your own plastic material.