On March 25, 2009, EPA proposed, in the Federal Register, revisions to EPA Methods 201A and Method 202. According to EPA, the proposed revisions to Method 201A would add a particle-sizing device to allow for sampling particulate matter (PM) with an aerodynamic diameter equal to or less than 2.5 micrometers (Ám). The proposed revisions to Method 202 would revise the sample collection and recovery procedures of the method in effort to reduce the formation of reaction artifacts that lead to inaccurate (biased) measurements of condensable particulate matter (CPM). Comments on EPA’s proposal must be received by the Agency on or before May 26, 2009.
RMB applauds EPA for finally acknowledging the flaws in Method 202 and taking action to minimize the inherent biases and imprecision in many of the measurements that have been made with Method 202. RMB is concerned that most if not all of the Agency’s work has been performed in a laboratory on simulated stack gas, and as such, the apparent reduction in method biases may not be fully realized in actual field measurements. RMB hopes that anyone with actual test data collected with the revised Method 202 procedures will provide those data to EPA during the comment period. We believe the Agency would most benefit from studies that compare existing Method 202 data with contemporaneous measurements obtained with the revised Method 202 procedures. (The revised Method 202 procedures have been available and posted on EPA’s web site as OTM 28 for several months.)
RMB Consulting &