EPA Proposes Revisions to the PM 2.5 NAAQS: How Much Will It Matter?

Last Thursday, in response to a court order, EPA finally proposed revisions to the national ambient air quality standard for PM2.5. The most significant part of the rule is EPA’s proposal to lower the primary annual standard from 15 ug/m3 to a range of from 12 ug/m3 to 13 ug/m3.

At a certain level, the proposal should not really be news and should not have a significant impact. After all, in 2009, the D.C. Circuit Court of Appeals rejected EPA’s proposal at that time to retain the 15 ug/m3 standard. The court concluded that EPA had not justified retaining the standard, particularly in light of the recommendation of EPA’s Clean Air Science Advisory Committee to lower the standard to a range of 12 ug/m3 to 14 ug/m3. Since then, the evidence supporting a lower standard has only grown stronger. Thus, EPA does not really have a choice. At some point, the court would get tired of remanding it to EPA and might instead simply impose a standard.

Moreover, EPA’s modeling shows that only two counties would fail to attain the new NAAQS in 2020 if the stand were 13 ug/m3; an additional four counties would be in nonattainment at 12 ug/m3. However, this prediction masks at least one important detail. EPA’s attainment assessment is based on the assumption that all of its air rules will survive court challenge and Congressional efforts to override them. It is those rules that provide the backbone to EPA’s conclusion.

Of course, EPA and the environmental NGOs would argue that that is only more reason why the rule is required. If EPA’s other rules are indeed implemented, then no-harm, no foul. Indeed, EPA’s cost-benefit analysis shows much smaller costs and benefits (though benefits still greatly exceed costs, according to EPA) from this rule than from EPA’s other recent air rules. On the other hand, precisely because the NAAQS is not itself an emissions limitation, and because EPA may not consider economics in formulating the NAAQS, promulgation of this rule will make any backsliding by Congress difficult. Once the NAAQS is in place, states are going to have to develop implementation plans that demonstrate compliance. If they cannot rely on the recently promulgated EPA rules, then they will have to develop alternative strategies.

One significant note for the regulated community. In order to provide some level of regulatory certainty, EPA is proposing that facilities that have projects in the PSD permitting pipeline will not have to demonstrate compliance with the new NAAQS so long as a draft permit or preliminary determination has been issued for public comment before the effective date of the revised NAAQS. Get those applications in early!

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