EPA Proposes To Tighten Annual PM2.5 Limit But Retain Daily Standard

January 6, 2023

EPA is proposing to tighten its health-based annual limit for fine particulate matter (PM2.5) to a level lower than that set by the Obama administration in 2012 but is not planning to tighten its 24-hour limit, disappointing environmental and public health groups and disregarding agency science advisers who pushed for a tougher daily value.

In its long-awaited proposal to revise national ambient air quality standards (NAAQS) for fine particles, the agency proposes to lower the current “primary,” or health-based limit for PM2.5 from 12 micrograms per cubic meter (ug/m3) down to a tougher limit in the range of 9 ug/m3 to 10 ug/m3.

“Our work to deliver clean, breathable air for everyone is a top priority at EPA, and this proposal will help ensure that all communities, especially the most vulnerable among us, are protected from exposure to harmful pollution,” EPA Administrator Michael Regan told reporters Jan. 5, ahead of the proposal’s release Jan. 6.

“This proposal to deliver stronger health protections against particulate matter is grounded in the best available science, advancing the Biden-Harris Administration’s commitment to scientific integrity and a rigorous scientific process,” Regan added.

Significantly, however, EPA leaves the rest of its suite of NAAQS for PM2.5 and the larger PM10 unchanged, including “secondary” limits designed to protect the environment, rather than human health directly.

This means the agency does not propose to tighten the 24-hour limit of 35 ug/m3, despite pressure to do so from environmental groups pressing for a limit of 25 ug/m3 and a majority of the agency’s Clean Air Scientific Advisory Committee (CASAC) seeking a new level set in the range of 25 ug/m3 to 30 ug/m3.

However, the agency is seeking comment on a potential tougher standard set at “as low as” 25 ug/m3.

“The Administrator proposes to conclude that the scientific evidence not clearly call into question the adequacy of the current standard,” EPA says in a fact sheet on the issue.

EPA’s proposal for the annual limit falls squarely within the range suggested by EPA staff of 8 ug/m3 up to 12 ug/m3, and the range of 8 ug/m3 to 10 ug/m3 backed by a large majority of CASAC members.

EPA will take comment, however, on potential standards set at 8 ug/m3 — the preferred level of many public health advocates — and 11 ug/m3 — the level preferred by one CASAC member.

Reducing emissions of PM2.5 is a key priority of the Biden administration, given the range and severity of adverse health effects blamed on fine particles, including lung and cardiovascular problems, and premature death. Reductions in PM2.5 pollution are also estimated by the agency to produce the largest monetized health benefits of any environmental rule.

Under the Clean Air Act, EPA must set the NAAQS at a level requisite to protect public health with an “adequate margin of safety,” and by law, EPA cannot consider implementation costs when setting the limits.

Nonattainment Findings

But tougher PM2.5 limits also mean that more parts of the country will likely be classified in NAAQS “nonattainment,” requiring states to impose tougher pollution controls on industry, with significant implementation costs.

The tougher the eventual final standards are, the more areas of the country will fall into nonattainment, raising compliance costs, sources say.

Industry attorneys also note that regardless of nonattainment status, industry permit applicants have to take into account the need to show they will not raise emissions that cause a NAAQS violation when designing their projects.

When pressed by reporters on the proposal’s possible costs, Regan did not directly answer, and referred only to agency estimates of the net benefits, which depend on the level EPA ultimately selects for the annual standard.

EPA says the proposed standard could result in net health benefits valued at up to $17 billion in 2032 for an annual standard of 10 ug/m3 and as much as $43 billion in 2032 for an annual standard set at 9 ug/m3.

Meanwhile, EPA is also proposing to revise its air quality monitoring regulations in order to facilitate implementation of a tougher PM2.5 limit.

“To enhance protection of air quality, especially in overburdened and vulnerable communities with environmental justice concerns subject to disproportionate air pollution risk, EPA is proposing to modify the PM2.5 monitoring network design criteria to include an environmental justice factor. This factor will account for proximity of populations at increased risk of PM2.5-related health effects to sources of air pollution,” EPA says in its fact sheet.

“EPA is also proposing other changes to improve the quality of monitoring data used in regulatory decision making and to better characterize air quality in communities that are at increased risk of PM2.5 exposure and health risk,” the agency says. — Stuart Parker (sparker@iwpnews.com)

Kathy Beckett
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