(1) No person shall be employed or permitted to work in compressed air until he has been examined by the medical officer and found to be physically qualified therefor.

(2) No person who has not previously worked in compressed air shall, during the first twenty-four hours of his employment, be permitted to work therein longer than one working-period, as provided in section ten,¹ and he shall not be permitted to resume such work, if the air pressure exceeds fifteen pounds, until he has been re-examined by the medical officer and found to be physically qualified therefor.

(3) No person who is employed in compressed air, but who has been absent therefrom for ten or more consecutive days for any cause, shall be permitted to resume such work until he has been re-examined by the medical officer and found to be physically qualified therefor.

(4) No person who has been employed regularly in compressed air for three months shall be permitted to continue such work until he has been re-examined by the medical officer and found to be physically qualified therefor.