(1) The requirements of this rule apply to any ambient air monitoring performed by the department or any other entity that is:
(a) required by this chapter;
(b) used to demonstrate compliance with this chapter;
(c) submitted in an application for, or to comply with a condition of, a permit under this chapter; or
(d) used to satisfy any applicable requirement of Title 75, chapter 2, MCA, or the federal Clean Air Act, 42 USC 7401 through 7671g, or implementing regulations, for which the department has oversight.
(2) Any entity performing ambient air monitoring within the state of Montana for a purpose listed in (1) shall perform it according to a Quality Assurance Project Plan (QAPP) prepared to satisfy the applicable requirements of 40 CFR Parts 50, 53, and 58. If the ambient air monitoring is to be performed to comply with subchapter 8 of this chapter, an entity shall also consider the EPA Ambient Monitoring Guidelines for Prevention of Significant Deterioration (PSD), EPA-450/4-87-007 (May 1987).
(3) If monitoring for a purpose in (1) is performed by:
(a) the department, it must be performed in compliance with the Montana Ambient Air Monitoring Program Quality Assurance Project Plan; or
(b) any other entity, it must be performed in compliance with a project-specific QAPP that has been submitted to and approved by the department.
(4) The department shall notify the entity in writing of approval, conditional approval, or disapproval within 60 days after receiving a project-specific QAPP required by (3)(b). If the department receives additional information in response to a notice of conditional approval or disapproval, the 60-day review period begins again.
(5) The department may invalidate, in whole or in part, ambient air monitoring data that was not obtained in compliance with this rule. Invalidated data may not be used for the purposes listed in (1).