Tighter PM2.5 Limit Would Cause Major Implementation Hurdles, Experts Say

Source: By Stuart Parker, Inside EPA • Posted: Sunday, October 16, 2022

An industry attorney and some state officials are expecting extensive difficulties for industry permit applicants and state air regulators if EPA were to significantly tighten federal air quality standards for fine particulate matter (PM2.5), including widespread nonattainment, as well as problems with air quality modeling, monitoring and treatment of wildfire smoke.

Speaking Oct. 12 during a virtual event hosted by the Air and Waste Management Association (A&WMA), attorney Joseph Stanko, a partner with Hunton Andrews Kurth, said there would be dramatic effects if EPA were to tighten the national ambient air quality standards (NAAQS) to the maximum degree recommended by agency staff and science advisers.

If EPA were to set the annual NAAQS at 8 micrograms per cubic meter (ug/m3), “almost every major center of economic activity” would find itself in “nonattainment” with the new standard, triggering the need for states to craft air plans with tougher control measures, and for industry permit applicants to undergo more rigorous permit reviews, Stanko said.

Many sources of air pollution would have an immediate need to secure “offsets” for their pollution, even before states could establish systems for offsets in their state implementation plans (SIPs) for air standards attainment, he explained. Nor would EPA be likely to issue necessary guidance in time to help industry, Stanko added.

Placing so much of the country into nonattainment would contrast dramatically with the current situation, where almost all areas outside of California are complying with the existing annual standard of 12 ug/m3.

Sources differ on how big the effect of a tougher PM2.5 NAAQS would be nationally, but generally agree that the effects would be most keenly felt in California and elsewhere in the West.

There would be “a dramatically greater impact this time around if the standard is changed,” Stanko said.

One issue that could compound compliance problems would be the computer modeling required by industry permit applicants to show that they would not “cause or contribute” to a NAAQS violation. “In general, these models are overpredicting the emissions,” Stanko said.

While there is disagreement about how much the models overpredict, there is “general agreement” that the models overestimate emissions, a problem that Stanko termed “modeling fizz.” This would be a more acute problem with a tougher NAAQS, he said.

Staff Assessment

EPA staff in a May 31 policy assessment document again recommended that the agency tighten the annual limit to between 8 ug/m3 and 12 ug/m3. The Trump EPA previously disregarded this advice, opting to retain its whole suite of PM standards in 2020. The Biden EPA is now reconsidering that decision, following litigation from environmentalists and others faulting the Trump-era review of the standards.

The White House Office of Management and Budget (OMB) is still reviewing EPA’s draft proposal that may seek to tighten the standards, and the agency is expected to issue the plan this fall. Stanko speculated that the agency may release the proposal after the Nov. 8 midterm elections, which would avoid potentially major controversy over implementation costs before voters go to the polls.

He said that, should EPA opt for the tougher end of staff’s suggested range, it would have a chilling effect on economic development and even lead to projects being sent “offshore” to avoid tougher air regulations. Stanko also noted that EPA does not have a legal obligation to reconsider the NAAQS in between the regular reviews required every five years under the Clean Air Act.

When setting NAAQS, EPA may not under Supreme Court precedent consider implementation costs. However, this reconsideration is discretionary, and the Obama administration previously opted not to tighten ozone standards in a similar proceeding, citing the disruption and cost that would be caused to industry and states, Stanko noted.

It is unclear if EPA would opt for a standard as stringent as 8 ug/m3, however. The agency’s Clean Air Scientific Advisory Committee (CASAC) recommended, by a 6-1 majority, tightening the annual limit to between 8-10 ug/m3. The panel’s majority also called for EPA to tighten the existing daily PM2.5 limit from 35 ug/m3 to a level between 25-30 ug/m3. EPA staff has not recommended tightening the daily limit.

The lone CASAC vote against the panel’s recommendation was Georgia air regulator James Boylan, who instead preferred tightening the annual limit to between 10-11 ug/m3. Boylan also opposed tightening the daily standard.

Speaking on the A&WMA call, Boylan said that in terms of implementation, a new standard would require EPA to look again at problems with air monitors reading inconsistently with each other.

States are increasingly turning to Federal Equivalent Methods (FEMs) that operate continuously and are cheaper than Federal Reference Methods (FRMs), which are the original benchmark for measuring NAAQS attainment. But FEMs are reading higher than the FRMs they are supposed to be equivalent to, by as much as 2.5 ug/m3 in some places, Boylan said, leading to a “meaningfully different” result.

EPA officials recently indicated that they intend to re-examine monitor performance issues in the near future. EPA air official Chet Wayland said at a Sept. 29 event hosted by the Association of Air Pollution Control Agencies that EPA intends to propose a revision to air monitoring regulations to “allow improvement of PM concentration measurement performance” for approved FEMs.

Wildfire Smoke

Meanwhile, Mary Uhl, executive director of the Western States Air Resources Council (WESTAR), a regional regulators’ group, said that tightening the PM2.5 NAAQS would further complicate attaining the standards, which is already challenging because of the increasing impacts of wildfire smoke.

Many air quality improvements in recent years are being “erased by wildfire smoke,” Uhl said. Under EPA’s exceptional events rule, states can exclude air monitoring data affected by the smoke from their demonstrations of NAAQS compliance, enabling them to avoid nonattainment entirely or a worsened category of nonattainment.

As the incidence of wildfire increases across the West, which has been experiencing a “megadrought,” regulators rely more and more on the exceptional events provision. But as the fires become more commonplace, some, including members of CASAC, are questioning whether they should be considered “exceptional” at all.

The CASAC majority is supporting a tighter daily PM2.5 limit to curb spikes in air pollution, but this would not help bring down wildfire pollution. Currently, EPA’s exceptional events rule allows wildfire smoke to be deemed an event worthy of a waiver, and EPA has indicated no intention to alter this, Uhl said.

If EPA tightens the PM NAAQS, this means “lots and lots of work ahead” for state regulators to prepare exceptional events requests, Uhl said. A change in air agencies’ prioritization of work would be required, along with more resources.

Some House Democrats are pressing EPA to adopt tougher standards, and they are supporting CASAC’s recommendation that EPA “consider potential pathways to better incorporate ‘exceptional events,’ like wildfires, into regulatory standards,” according to lawmakers’ July 11 letter to the agency.

“We support the recommendation that EPA rethink about how best to capture exceptional events so that public health is prioritized,” the lawmakers said. — Stuart Parker (sparker@iwpnews.com)