On August 9, 2019 EPA proposed the Prevention
of Significant Deterioration (PSD) and Nonattainment New Source Review (NNSR):
Project Emissions Accounting regulation to clarify and eliminate
uncertainty relating to Step 1 of the New Source Review applicability process.
EPA had previously issued the Project
Emissions Accounting Under the New Source Review Preconstruction Program
memorandum explaining that EPA interprets NSR regulations to allow emissions
decreases, as well as increases, to be considered during Step 1 of the NSR
applicability process as long as the decreases and increases are part of the
single project being assessed. The August 2019 rule proposes revisions to the
NSR regulations to codify this approach of including both increases and
decreases resulting from the project. The rule also proposes to withdraw the
Project Netting Proposal released in 2006. The comment period for the proposed
rule closes on October 8, 2019.