15 SEP 93
steps to form non-gaseous radioactive isotopes with short half-
lives. Four of these successive decay products have half lives less
than 30 minutes. These isotopes are chemically reactive and attach
to building surfaces and airborne dust particles. Both attached and
unattached decay products can be inhaled and attach to lung tissue.
Further radioactive decay of these isotopes releases alpha particles
that damage lung tissue and leads to lung cancer.
EPA recommends the removal of radon gas rather than removal of decay
products with high efficiency air filters or air cleaning devices.
For more information on the disadvantages of air cleaning as the
primary method for radon control, refer to EPA 625/5-87/019, Radon
Reduction Techniques for Detached Houses, Paragraph E.2.5. and
6. PRIORITY OF FACILITY TYPES: Priorities for designing various
types of military facilities to reduce indoor radon are based upon the
a. Priority 1: Day care centers, hospitals, schools, living
quarters including barracks, unaccompanied personnel housing
(officers and enlisted) and family housing, and routinely
occupied spaces below grade.
c. Priority 3: All other routinely occupied structures including
morale, welfare and recreational facilities.
d. Priority 4: All intermittently occupied structures that are
used by any military or civilian employee whose total work
time in those buildings equals or exceeds 80 hours per year.
e. Structures occupied less than 80 hours per year by any
employee do not require radon preventive measures.
7. INDOOR RADON CONCENTRATION AND ACTION LEVELS: Radon is measured
in picocurries per liter (pCi/l) of air. EPA studies have assigned
relative health risks for various concentration levels of indoor radon
based upon periods of exposure; concentration levels below 4 pCi/l are
The action levels given below conform to AR 200-1, Chapter 11:
a. Negligible : 0 to 4 pCi/l.
: 4 to 8 pCi/l.
: 8 to 20 pCi/l.
d. High : 20 to 200 pci/l.