Section 146(4) in The Coal Mines Regulations, 2011
(4)The samples drawn under sub-regulation (3) shall as far as practicable, be representative of the levels of dust exposure of work-persons and for this purpose, the sampler shall be positioned on the return side of the point of dust generation and within I metre of the normal working position of but not behind the operator or other worker whose exposure is deemed to be maximum in his working group.
