(a) The department may exempt a proposed new or modified facility from the requirements of section 231-12.3 of this Subpart with respect to monitoring for a particular regulated NSR contaminant, if:

1. (1) the emissions increase of the regulated NSR contaminant from the proposed new or modified facility would cause, in any attainment area, air quality impacts less than the following deminimis monitoring levels:

   Carbon Monoxide	575 µg/m3, 8-hour average;
   Nitrogen dioxide	14 µg/m3, annual average;
   Particulate matter (PM-10)	10 µg/m3, 24-hr average;
   PM-2.5	0µg/m3, 24-hr. average;
   Sulfur dioxide	13 µg/m3, 24-hour average;
   Ozone1	see footnote
   Elemental lead	0.1 µg/m3, 3-month average;
   Fluorides	0.25 µg/m3, 24-hour average;
   Total and reduced sulfur	10 µg/m3, 1-hour average;
   Hydrogen sulfide	0.2 µg/m3, 1-hour average; or

2. (2) the concentrations of the regulated NSR contaminant in the area that the facility would affect are less than the concentrations listed in paragraph (1) of this subdivision.

(b) In cases where the source impacts are above the deminimis monitoring levels of paragraph (a)(1) of this section, the department may waive the requirements of section 231-12.3 of this Subpart with respect to monitoring for a particular regulated NSR contaminant for which an applicant makes an acceptable showing that:

1. (1) representative existing ambient air monitoring data exists in the affected area and is of the quality and nature which demonstrates the current conditions of the area's air quality; or
2. (2) representative ambient air monitoring data exists from a prior time period which can be demonstrated to be conservative (i.e., higher) in establishing the current conditions of the area's air quality.