§ 74.8 - Measurement, accuracy, and reliability requirements.

§ 74.8 Measurement, accuracy, and reliability requirements.

(a) Breathing zone measurement requirement. The CPDM shall be capable of measuring respirable dust within the personal breathing zone of the miner whose exposure is being monitored.

(b) Accuracy. The ability of a CPDM to determine the true concentration of respirable coal mine dust at the end of a shift shall be established through testing that demonstrates the following:

(1) For full-shift measurements of 8 hours or more, a 95 percent confidence that the recorded measurements are within ±25 percent of the true respirable dust concentration, as determined by CMDPSU reference measurements, over a concentration range from 0.2 to 4.0 mg/m³; and

(2) For intra-shift measurements of less than 8 hours, a 95 percent confidence that the recorded measurements are within ±25 percent of the true respirable dust concentration, as determined by CMDPSU reference measurements, over the concentration range equivalent to 0.2 to 4.0 mg/m³ for an 8-hour period.^[1]

(c) Reliability of measurements. The CPDM shall meet the accuracy requirements under paragraph (b) of this section, regardless of the variation in density, composition, size distribution of respirable coal mine dust particles, and the presence of water spray mist in coal mines.

(d) Precision. The precision of the CPDM shall be established through testing to determine the variability of multiple measurements of the same dust concentration, as defined by the relative standard deviation of the distribution of measurements. The relative standard deviation shall be less than 0.1275 without bias for both full-shift measurements of 8 hours or more, and for intra-shift measurements of less than 8 hours within the dust concentration range equivalent to 0.2 to 4.0 mg/m³ for an 8-hour period, as specified under paragraph (b)(2) of this section.

(e) Bias. The bias of the CPDM measurements shall be limited such that the uncorrectable discrepancy between the mean of the distribution of measurements and the true dust concentration being measured during testing shall be no greater than 10 percent. Bias must be constant over the range of dust concentration levels tested, 0.2 to 4.0 mg/m³ for an 8-hour sampling period.

(f) Testing conditions. Laboratory and mine testing of the CPDM for accuracy, precision, bias, and reliability under diverse environmental conditions (as defined under § 74.7(e) and (g)) shall be determined using the NIOSH testing procedure, “Continuous Personal Dust Monitor Accuracy Testing,” June 23, 2008, available at: http://www.cdc.gov/niosh/mining/pubs/pubreference/outputid3076.htm. All testing results shall be submitted to NIOSH in writing on the application filed under § 74.11.

(1) Persons must proceed in accordance with NIOSH testing procedure “Continuous Personal Dust Monitor Accuracy Testing,” June 23, 2008. The Director of the Federal Register approves this incorporation by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Persons may obtain a copy at the address below: NIOSH-Publications Dissemination, 4676 Columbia Parkway, Cincinnati, OH 45226. http://www.cdc.gov/niosh/mining.

(2) Persons may inspect a copy at MSHA, Office of Standards, Regulations, and Variances, 201 12th Street South, Arlington, VA 22202-5452; 202-693-9440; or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.\n.

[75 FR 17523, Apr. 6, 2010, as amended at 80 FR 52990, Sept. 2, 2015]

Footnotes - 74.8

^[1] The equivalent dust concentration range to the 8-hour range of 0.2 − 4 mg/m³ is calculated by multiplying this 8-hour range by the dividend of eight hours divided by the duration of the intrashift measurement specified in units of hours. For example, for a measurement taken at exactly one hour into the shift, the 8-hour equivalent dust concentration range would be a one-hour average concentration range of: 8 hours/1 hour × (0.2 − 4 mg/m³) = 1.6 − 32 mg/m³; for a two-hour measurement, the applicable concentration range would be calculated as: 8 hours/2 hours × (0.2 − 4 mg/m³) = 0.8 − 16 mg/m³; for a 4-hours measurement, the equivalent range would be: 0.4 − 8 mg/m³; * * * etc. A CPDM must perform accurately, as specified, for intrashift measurements within such equivalent concentration ranges.