In part, the senators wrote:

“The EPA’s proposal fails to consider several important factors that will make implementation of a lower annual standard extremely difficult, or in some cases impossible, to no measurable benefits to public health, the environment, or the economy. The EPA should not finalize a discretionary reconsideration of a PM2.5 NAAQS that is unattainable and will likely lack an accompanying, detailed implementation plan.”

Full text of the letter may be found here and below.

September 20, 2023 

The Honorable Michael S. Regan

Administrator

US Environmental Protection Agency

Dear Administrator Regan:

On December 18, 2020, the Environmental Protection Agency (EPA) completed its comprehensive review and published a final decision to retain the Obama Administration’s 2013 National Ambient Air Quality Standards (NAAQS) for particulate matter (PM). Thirty-three days later, the Biden Administration issued an executive order directing the EPA to undertake a reconsideration of that decision. On January 27, 2023, the EPA published a discretionary proposal to revise the primary annual fine particulate matter (PM2.5) standard by lowering the level from 12 µg/m3 to between 9-10 µg/m3, an up to 25-percent reduction. Additionally, the EPA sought comment on an alternative standard as low as 8 µg/m3 – as much as 33 percent lower than the current standard.

According to the World Health Organization our nation enjoys some of the cleanest air in the world. The EPA’s own figures report that direct emissions of PM2.5 are down 40 percent from 1990 levels and annual ambient PM2.5 concentrations have decreased 43 percent between 2000 and 2019. Considering this progress in improving our air quality and the limited percentage of PM emissions from stationary point sources subject to the relevant regulation, the EPA should heed the advice of experts that it is neither necessary nor advisable to revise the primary annual PM2.5 standard and rescind the proposed reconsideration.

Establishing a lower NAAQS does not directly limit emissions. Rather, it establishes a level of ambient pollution that the Administrator determines is “requisite to protect the public health” with “an adequate margin of safety” and it falls to the states to implement procedures and pollution controls to attain and maintain the standards.

However, as the PM2.5 standard is approaching natural background levels, there are fewer sources available to regulate in order to achieve compliance. According to the Association of Air Pollution Control Agencies, wildfires and miscellaneous sources accounted for over 70 percent of domestic PM2.5 emissions in 2022.  The EPA’s Policy Assessment for the PM NAAQS reconsideration estimated that only 16 percent of PM2.5 emissions come from power plants and industrial sources, while the vast majority of the emissions are from non-point sources, such as wildfires, construction, road dust, and international transport. 

Many of these non-point sources are exceedingly onerous or impossible to control, or like wildfires, are beyond the scope of the Clean Air Act’s regulatory authorities. In light of this, sharply lowering the current PM2.5 annual standard would increase nonattainment levels across the country. This would increase permitting and regulatory burden on manufacturers, energy producers and several other key industries to our economy without a feasible path to attainment given the high costs and diminishing returns of additional control technologies.

This would result in Americans inheriting all of the negative consequences of nonattainment: offshoring of our domestic manufacturing, job loss, electric reliability concerns, higher prices, reliance on China, energy insecurity, and slow economic growth. At the same time, it would produce little to no measurable public health or environmental benefits. This proposal, particularly with its confounding inclusion of a request for comments on a standard as low as 8 µg/m3 that the EPA attests it is not even considering, is already causing uncertainty in the business community. This uncertainty is negatively impacting investments that would create good-paying jobs, including in the renewable energy sector the Biden Administration professes to support.

The EPA’s proposal fails to consider several important factors that will make implementation of a lower annual standard extremely difficult, or in some cases impossible, to no measurable benefits to public health, the environment, or the economy. The EPA should not finalize a discretionary reconsideration of a PM2.5 NAAQS that is unattainable and will likely lack an accompanying, detailed implementation plan. With that, I urge the EPA to rescind its proposed reconsideration of the PM2.5 NAAQS, and review the NAAQS under the Clean Air Act’s regular five-year review schedule. At that time, the EPA must set standards that follow the science and operate within the bounds of what is technologically and economically feasible.