An employer shall ensure that every workplace in his undertaking is ventilated either by natural or mechanical
means in such a way that -
(a) the air breathed by employees does not endanger their safety;
(b) the time-weighted average concentration of carbon dioxide therein, taken over an eight-hour period, does
not exceed one half per cent by volume of air;
(c) the carbon dioxide content thereof does not at any time exceed three per cent by volume of air;
(d) the prescribed exposure limits for airborne substances therein are not exceeded; and
(e) the concentration therein of any explosive or flammable gas, vapour or dust does not exceed the lower explosive limit of that gas, vapour or dust.