The Environmental Protection Agency (EPA) is taking direct final action to update a procedure in the New Source Performance Standards (NSPS). The procedure provides the ongoing quality assurance/ quality control (QA/QC) procedures for assessing the acceptability of particulate matter (PM) continuous emissions monitoring systems (CEMS). The procedure explains the criteria for passing an annual response correlation audit (RCA) and the criteria for passing an annual relative response audit (RRA). The procedure currently contains a requirement that the annual QA/QC test results for affected facilities must fall within the same response range that was used to develop the existing PM CEMS correlation curve. As a result, some facilities are unable to meet the criteria for passing their annual QA/QC test because their emissions are now lower than the range previously set during their correlation testing. We are modifying the procedure to allow facilities to extend their PM CEMS correlation regression line to the lowest PM CEMS response obtained during the annual RCA or RRA, when these PM CEMS responses are less than the lowest response used to develop the existing correlation curve. This change will ensure that facilities that have reduced their emissions since completing their correlation testing will no longer be penalized because their lower emissions fall outside their initial response range. This action also corrects a typographical error in the procedure.