White House Clears EPA Plan To Likely Tighten PM2.5 Limits For Release

Source: By Stuart Parker, Inside EPA • Posted: Monday, January 2, 2023

The White House Office of Management and Budget (OMB) has completed interagency review of EPA’s keenly anticipated proposal that is expected to tighten air standards for fine particulate matter (PM2.5), moving the agency closer to releasing the plan that is certain to prove controversial, given its environmental and economic implications.

According to OMB’s website, the proposal cleared review Dec. 27, weeks after environmental groups had hoped the agency would issue it.

But some sources believe the proposal took longer to clear OMB than it might otherwise have because of concerns raised by other federal agencies, resulting in an extended review. EPA sent the proposal for review in August, and OMB review typically takes up to 90 days, but can be faster or slower, depending on the circumstances.

The rule could have potentially major implications for public health and the economy, depending on how much EPA tightens the national ambient air quality standards (NAAQS) for PM 2.5.

For example, some industry sources fear extensive difficulties for industry permit applicants and state air regulators if EPA were to significantly tighten the NAAQS for PM2.5, including widespread nonattainment, as well as problems with air quality modeling, monitoring and treatment of wildfire smoke.

EPA is reconsidering the Trump administration’s 2020 decision to leave the entire suite of NAAQS for PM2.5 and the larger PM10 unchanged from the levels set in 2012 by the Obama EPA.

Agency staff has now twice recommended tightening the “primary,” or health-based limit for PM2.5 from 12 micrograms per cubic meter (ug/m3) down to a tougher level between 8 ug/m3 and 12 ug/m3, a recommendation that Trump EPA Administrator Andrew Wheeler opted to overrule. Wheeler relied for support on the position of the Trump-era Clean Air Scientific Advisory Committee (CASAC), which saw no evidence that would compel tougher standards.

But a majority of the reconstituted Biden-era CASAC now supports a tougher annual standard in the range 8 ug/m3 to 10 ug/3, with one member favoring a slight tightening to perhaps 11 ug/m3. It is therefore considered highly likely that EPA will tighten at least the annual limit, but by how much is uncertain.

There is also uncertainty over whether and by how much EPA might opt to tighten the daily health-based limit for PM2.5, which now stands at 35 ug/m3.

While EPA staff has not recommended tightening the daily limit, a majority of CASAC members recommend tightening it down to a level between 25 ug/m3 and 30 ug/m3. Environmental groups have also pressed the agency to tighten the limit, down to 25 ug/m3.

Any tightening of the daily limit would be intended to control short-lived spikes of air pollution, such as those that might arise from use of wood-burning stoves during the winter, when atmospheric conditions can trap pollutants.

But problematically high short-term levels of PM2.5 and PM10 are often driven by events such as wildfires and dust storms. Such occurrences can qualify as “exceptional events” and therefore not count toward regulatory limits, although their public health effects can be very harmful. Air regulators can do little to mitigate such situations.

Adverse Health Effects

PM2.5 is associated with a range of harmful effects, including premature death, and reductions in PM2.5 therefore drive the largest estimated public health benefits of any pollutant regulated by EPA rules. So, a deep cut in PM2.5 levels would be expected to provide major health benefits that can at least in part be quantified and monetized.

PM2.5 is also a pollutant of concern in many environmental justice (EJ) communities, and reducing it is important to the Biden EPA’s agenda of promoting EJ causes.

By law, EPA cannot consider implementation costs when setting the level of the NAAQS, and costs may only be considered later at the implementation phase. Nonetheless, any tightening of the PM2.5 standards is likely to bring significant implementation costs for states and industry.

The extent of these costs depends how much EPA opts to tighten the limits. Sources say a minor tightening of the annual primary PM2.5 limit, for example, would have relatively little impact outside of California and a few other air pollution hotspots. Much of the country would already meet the new limit, and most states would not have to draw up state implementation plans (SIPs) to come back into attainment, or institute new pollution controls. California would not meet any tougher limits, given its entrenched problems with air quality.

But a sweeping tightening of annual and possibly daily PM2.5 limits could bring much of the country into “nonattainment,” requiring SIPs and control measures. Industry lawyers also note that tougher NAAQS must be taken into account in permitting industrial facilities, introducing new complication and costs, and potentially prohibiting industrial development in some areas.

Tougher NAAQS are therefore likely to meet with praise from environmentalists, but also possibly frustration if the agency does not go as far as some groups would like. Industry and some states would likely be critical of tougher limits, and litigation over the eventual rule, once finalized, is all but inevitable. — Stuart Parker (sparker@iwpnews.com)

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