An employer or a self-employed person shall forthwith review the assessment required by subregulation (1) if-
(a) there is reason to believe that the previous assessment is no longer valid;
(b) control measures are no longer efficient;
(c) technological or scientific advances allow for more efficient control methods; or (d) there has been a significant change in-
(i) work methods;
(ii) the type of work carried out; or
(iii) the type of equipment used to control exposure, and subregulations (2) and (3) shall apply.