Section 90.202 - Certified person; sampling(a) The respirable dust sampling required by this part shall be performed by a certified person.(b) To be certified, a person shall complete the applicable MSHA course of instruction and pass the MSHA examination demonstrating competency in sampling procedures. Persons not certified in sampling and those certified only in maintenance and calibration procedures in accordance with § 90.203(b) are not permitted to collect respirable dust samples required by this part or handle approved sampling devices when being used in sampling.(c) To maintain certification, a person must pass the MSHA examination demonstrating competency in sampling procedures every three years.(d) MSHA may revoke a person's certification for failing to properly carry out the required sampling procedures.