An employer shall ensure that -
(a) where it is possible for employees to open, close, adjust or secure windows skylights and ventilators -
(i) it may be done safely, and
(ii) when open, such windows, skylights and ventilators are not positioned so as to constitute a hazard to employees, and
(b) windows and skylights can be cleaned without risk to the safety, health or welfare of persons carrying out this work or of other persons present -
(i) by design,
(ii) by being fitted with devices, or
(iii) in conjunction with the use of equipment.