In this guidance, EPA recognizes industry concerns on the high biased results that Method 202 often yields and states that it may revise the method. In the interim, EPA recommends that permitting agencies and permit applicants deviate from Method 202 – specifically allowing applicants to use field train proof blanks in lieu of field train recovery blanks and to allow blank values as high as 5.1 mg to be used in the calculation of condensable PM. The current upper limit for field train recovery blanks is 2.0 mg. EPA states that the guidance may be used for these purposes:
- PSD and NAA-NSR PM10 and PM2.5 source applicability;
- PSD air quality analyses;
- NAA-NSR emissions offset quantification; and
- PSD and NAA-NSR compliance tests.
EPA also recognizes issues with PM2.5 emission factors in AP-42 and states that it prefers stack testing for PSD and NAA-NSR purposes. EPA also advises caution when using existing Method 202 condensable data, given the changes in the test method that have occurred over the past few years. This is a good reminder that when performing PSD applicability determinations for PM10 and PM2.5, especially for larger sources, facilities should closely consider conducting before-and-after stack testing for PM filterable and condensable PM.
For more information, contact your EPS consultant.