«2-
,
A total of 33 structures were examined.
These were in various
ptages of construction that varied from floor slab only to essentially
complete and occupied (by the contractor supervisor).
of the structures are shown in Figure l.
The locations
Figure 2 is a sketch of a
completed dwelling.
A typical building layout is indicated in Figure 3, showing the
points at which measurements were made: on the center line of each
wall, 10 feet out from the wall, 3 feet above the surface of the ground;
in the center of the building, at a height of 3 feet; and in the center
of the building, on the floor.
FINDINGS
Raw Data
The exposure rates measured are indicated in Table 1, in micro
roentgens per hour (uR/h).
External exposure rates ranged from 7 uR/hr
A
to 55 pR/hr, with an arithmetic mean value of 20 uR/hr.
Treated Data and Results
Exposure rate reduction factors (RF) were computed for each dwelling
except for seven "slab only" sites where no external measurements were
made.
The reduction factor (RF) is expressed in percent and was de-
termined utilizing the following equation:
RF = (1 - Interior Exposure Rate) x 100
Exterior Exposure Rate