(a) In all mines at least one sample shall be taken in exhaust mine
air by a competent person to determine if concentrations of radon daughters
are present. Sampling shall be done using suggested equipment and procedures
described in section 14.3 of ANSI N13.8-1973, entitled "American National
Standard Radiation Protection in Uranium Mines," approved July 18, 1973,
pages 13-15, by the American National Standards Institute, Inc., which is
incorporated by reference and made a part of the standard or equivalent
procedures and equipment acceptable to the Administrator, Metal and Nonmetal
Mine Safety and Health, Mine Safety and Health Administration. This
publication may be examined at any MSHA Metal and Nonmetal Mine Safety
and Health district office , or may be
obtained from the American National Standards Institute, Inc., 25 W.
43rd Street, 4th Floor, New York, NY 10036; http://www.ansi.org
. The mine operator may request that the required
exhaust mine air sampling be done by the Mine Safety and Health
Administration. If concentrations of radon daughters in excess of 0.1 WL are
found in an exhaust air sample, thereafter--
(1) Where uranium is mined--radon daughter concentrations representative of
worker's breathing zone shall be determined at least every two weeks at
random times in all active working areas such as stopes, drift headings,
travelways, haulageways, shops, stations, lunch rooms, magazines, and any
other place or location where persons work, travel, or congregate. However,
if concentrations of radon daughters are found in excess of 0.3 WL in an
active working area, radon daughter concentrations thereafter shall be
determined weekly in that working area until such time as the weekly
determinations in that area have been 0.3 WL or less for 5 consecutive
weeks.
(2) Where uranium is not mined--when radon daughter concentrations between 0.1
and 0.3 WL are found in an active working area, radon daughter concentration
measurements representative of worker's breathing zone shall be determined at
least every 3 months at random times until such time as the radon daughter
concentrations in that area are below 0.1 WL, and annually thereafter. If
concentrations of radon daughters are found in excess of 0.3 WL in an active
working area radon daughter concentrations thereafter shall be determined at
least weekly in that working area until such time as the weekly
determinations in that area have been 0.3 WL or less for 5 consecutive
weeks.
(b) If concentrations of radon daughters less than 0.1 WL are found
in an exhaust mine air sample, thereafter:
(1) Where uranium is mined--at least one sample shall be taken in the exhaust
mine air monthly.
(2) Where uranium is not mined--no further exhaust mine air sampling is
required.
(c) The sample date, locations, and results obtained under (a) and
(b) above shall be recorded and retained at the mine site or nearest mine
office for at least two years and shall be made available for inspection by
the Secretary or his authorized representative.
