Section 70.1900 - Exhaust Gas Monitoring(a) During on-shift examinations required by § 75.362 , a certified person as defined by § 75.100 of this chapter and designated by the operator as trained or experienced in the appropriate sampling procedures, shall determine the concentration of carbon monoxide (CO) and nitrogen dioxide (NO2): (1) In the return of each working section where diesel equipment is used, at a location which represents the contribution of all diesel equipment on such section;(2) In the area of the section loading point if diesel haulage equipment is operated on the working section;(3) At a point inby the last piece of diesel equipment on the longwall or shortwall face when mining equipment is being installed or removed; and(4) In any other area designated by the district manager as specified in the mine operator's approved ventilation plan where diesel equipment is operated in a manner which can result in significant concentrations of diesel exhaust.(b) Samples of CO and NO2 shall be- (1) Collected in a manner that makes the results available immediately to the person collecting the samples;(2) Collected and analyzed by appropriate instrumentation which has been maintained and calibrated in accordance with the manufacturer's recommendations; and(3) Collected during periods that are representative of conditions during normal operations.(c) Except as provided in § 75.325(j) of this chapter, when sampling results indicate a concentration of CO and/or NO2 exceeding an action level of 50 percent of the threshold limit values (TLV®) adopted by the American Conference of Governmental Industrial Hygienists, the mine operator shall immediately take appropriate corrective action to reduce the concentrations of CO and/or NO2 to below the applicable action level. The publication, "Threshold Limit Values for Substance in Workroom Air" (1972) is incorporated by reference and may be inspected at MSHA's Office of Standards, Regulations, and Variances, 201 12th Street South, Arlington, VA 22202-5452; 202-693-9440; at any MSHA Coal Mine Safety and Health District Office; 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. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 . In addition, copies of the document may be purchased from the American Conference of Governmental Industrial Hygienists, 1330 Kemper Meadow Drive, Attn: Customer Service, Cincinnati, OH 45240; 513-742-2020; http://www.acgih.org.(d) A record shall be made when sampling results exceed the action level for the applicable TLV ® for CO and/or NO2. The record shall be made as part of and in the same manner as the records for hazards required by § 75.363 of this chapter and include the following:(1) Location where each sample was collected;(2) Substance sampled and the measured concentration; and(3) Corrective action taken to reduce the concentration of CO and/or NO2 to or below the applicable action level.(e) As of November 25, 1997 exhaust gas monitoring shall be conducted in accordance with the requirements of this section.61 FR 55526, Oct. 25, 1996, as amended at 67 FR 38385 , June 4, 2002; 71 FR 16667 , Apr. 3, 2006; 80 FR 52989 , Sept. 2, 2015