Notwithstanding the provisions of regulation 4 (3), every employer of employees who at a workplace -
(a) are exposed to a hazardous chemical substance or a hazardous biological agent;
(b) come into physical contact with any known poisonous substance, which may cause illness if taken orally;
(c) are exposed to dirt, dust, soot or similar filth; or
(d) handle or process untanned hides or skins, or unwashed wool or mohair, shall provide a separate dining-room or eating place on the premises which in respect of the maximum number of employees who will be using.