13.—(1) The Executive may by a certificate in writing exempt employers from the requirements of regulations 4(1) and 7 in relation to one or more work activities.
(2) An exemption under paragraph (1) shall be limited in time and subject to the conditions that—
(a)the exposure of employees to electromagnetic fields is as low as is reasonably practicable; and
(b)employees are protected against any health effects and safety risks related to that exposure.
(3) The Executive may amend or revoke an exemption at any time by a further certificate in writing.