Section 90.206 - [Effective 4/14/2025] Exercise of option or transfer sampling(a) The operator shall take five valid representative dust samples for each part 90 miner within 15 calendar days after:(1) The 20-day period specified for each part 90 miner in § 90.100 ; and(2) Implementing any transfer after the 20th calendar day following receipt of notification from MSHA that a part 90 miner is employed at the mine.(b) Noncompliance with the standard shall be determined in accordance with § 90.207(d) .(c) Upon issuance of a citation for a violation of the standard, the operator shall comply with § 90.207(f) . 89 FR 28484 , 6/17/2024; 6/17/2024; 89 FR 28484 , 4/14/2025