20.—(1) Every employer who designates an area as a controlled or supervised area shall take such steps as are necessary (otherwise than by use of assessed doses of individuals), having regard to the nature and extent of the risks resulting from exposure to ionising radiation, to ensure that levels of ionising radiation are adequately monitored for each such area and that working conditions in those areas are kept under review.
(2) Adequate monitoring referred to in paragraph (1) shall include—
(a)in relation to areas designated on the basis of external radiation, measurement of dose rates (averaged over a suitable period if necessary); and
(b)in relation to areas designated on the basis of internal radiation, measurements where appropriate of air activity and surface contamination taking into account the physical and chemical states of the radioactive contamination.
(3) The employer upon whom a duty is imposed by paragraph (1) shall provide suitable and sufficient equipment for carrying out the monitoring required by that paragraph, which equipment shall—
(a)be properly maintained so that it remains fit for the purpose for which it was intended; and
(b)be adequately tested and examined at appropriate intervals.
(4) Equipment provided pursuant to paragraph (3) shall not be or remain suitable unless—
(a)the performance of the equipment has been established by adequate tests before it has first been used; and
(b)the tests and examinations carried out pursuant to paragraph (3) and sub-paragraph (a) have been carried out by or under the supervision of a suitably qualified person.
(5) The employer upon whom a duty is imposed by paragraph (1) shall—
(a)make suitable records of the results of the monitoring carried out in accordance with paragraph (1) and of the tests carried out in accordance with paragraphs (3) and (4);
(b)ensure that the records of the tests carried out in accordance with paragraphs (3) and (4) are authorised by a suitably qualified person; and
(c)keep the records referred to in sub-paragraph (a), or copies of those records, for at least 2 years from the respective dates on which they were made.
(6) Suitable records of the results of the monitoring referred to in paragraph 5(a) shall include—
(a)in relation to areas designated on the basis of external radiation, an indication of the nature and quality of the radiation in question;
(b)in relation to areas designated on the basis of internal radiation, an indication, where appropriate, of the nature and physical and chemical states of the radioactive contamination.