Section 143(4) in The Coal Mines Regulations, 2017
(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 one meter 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.
