EPA Issues New Ozone and PM2.5 SILs Guidance

Posted by Eric Hiser, May 28, 2018

On April 17, 2018, Peter Tsirigotis, Director of the Office of Air Quality Planning and Standards (OAQPS) issued a guidance memorandum, “Guidance on Significant Impact Levels for Ozone and Fine Particles in the Prevention of Significant Deterioration Permitting Program,” (Guidance) which establishes EPA’s current approach to significant impact levels” (SILs) used in the Prevention of Significant Deterioration (PSD) modeling program, but which likely may have some broader implications as well. The 112-page Guidance package sets forth EPA’s new approach to setting SILs and also provides the legal and technical rationale supporting the rule. This first installment looks at the policy issues. Later installments will examine the legal and technical issues in more detail.