On Aril 17, 2023, Texas Attorney General (AG) Ken Paxton issued a press release announcing he was joining 18 other AGs in providing critical commentary on the EPA’s proposed rule to alter the National Ambient Air Quality Standards (NAAQS) for particulate matter (PM).

In the commentary letter, the AGs state, “The EPA should withdraw the proposed change. The Proposed Rule exceeds the EPA’s statutory authority under the Clean Air Act (CAA), fails to offer sufficient scientific evidence demonstrating a need to revise the NAAQS, and imposes real harm. We, therefore, urge the EPA to withdraw the Proposed Rule and maintain the current NAAQS.”

Many in industry oppose the proposed rule, as well. Comments submitted by the Associated General Contractors of America (AGCA) reflect construction industry concerns, which include:

• Restrictions on equipment use
• Loss of federal highway funding
• Potential economic impacts such as construction bans leading to:
• “a massive layoff of construction workers and of workers who supply a multitude of materials, equipment, and services to construction”
• “a negative impact on GDP as well as a significant loss of jobs by construction service providers”
• A loss of manufacturing shipments to supply construction projects
• Construction bans that would impede projects to improve municipal water supplies and wastewater treatment facilities located throughout the nation
• Further supply chain disruption caused by curtailments on plant production for necessary construction materials

Regulatory background

The CAA requires the EPA to set national air quality standards for six criteria air pollutants considered harmful to public health and the environment:

• PM
• Ground-level ozone
• Lead
• Carbon monoxide
• Sulfur dioxide
• Nitrogen dioxide

PM is the term for a mixture of solid particles and liquid droplets found in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope.

Particle pollution includes:

• PM10: Inhalable particles with diameters that are generally 10 micrometers (µ) and smaller.
• PM2.5: Fine inhalable particles with diameters that are generally 2.5 µ and smaller. A single human hair is approximately 70 µ, so it’s about 30 times larger than the largest fine particle.

When the EPA establishes a new NAAQS or revises an existing standard for a criteria air pollutant, it sets in motion a series of actions aimed at ensuring air quality throughout the country meets those standards.

The EPA must designate areas as meeting (attainment) or not meeting (nonattainment) the standard. The CAA requires states to develop a general plan to attain and maintain the standards in all areas of the country and a specific plan to attain the standards for each area designated nonattainment. These plans, known as state implementation plans (SIPs), are developed by state and local air quality management agencies and submitted to the EPA for approval.

The SIPs serve two main purposes:

1. Demonstrate the state has the basic air quality management program components in place to implement a new or revised NAAQS.
2. Identify the emissions control requirements the state will rely on to attain and/or maintain the primary and secondary NAAQS.

Proposed rule

The proposed rule calls for a revision to the primary annual PM2.5 by lowering the level from 12 micrograms (µg) per cubic meter to a level between 9 and 10 µg per cubic meter. A microgram is 1 millionth of a gram. The Agency says the lower range reflects “the latest health data and scientific evidence,” and it asked for comments on the full range (between 8 and 11 µg per cubic meter) included in the Clean Air Scientific Advisory Committee’s (CASAC) latest report.

The Agency also proposes:

• To retain the current primary 24-hour PM2.5 standard
• To retain the primary 24-hour PM10 standard
• To retain the secondary 24-hour PM2.5 standard
• To retain the secondary annual PM2.5 standard
• To retain the secondary 24-hour PM10 standard
• Revisions to other key aspects related to the PM NAAQS, including revisions to the Air Quality Index (AQI) and monitoring requirements for the PM NAAQS

NAAQS controversy

“The [CAA] requires that EPA review the NAAQS every five years to ensure their adequacy. The review process is a multi-stage, robust review of the current science that requires significant expert input. If a standard is tightened, there is a cascading effect on air quality policies and programs across the country. States and local regions must ensure that the sources of pollution in their jurisdiction decrease their emissions, so that the region can meet the new, more stringent national standard,” according to the Harvard Environmental and Energy Law Program website. “Under the Trump administration, EPA weakened the five-year review of the NAAQS, by eroding the science-based review process and altering the membership requirements of CASAC. The Biden administration’s EPA has reinstated the CASAC membership requirements and is reviewing the science underlying the 2020 ozone and [PM] NAAQS.”

The daily and annual limits for soot pollution haven’t been lowered since 2012.

“Despite overwhelming evidence that the 2012 soot limits were not adequately protective of public health, the Trump EPA left those limits in place in a rushed December 2020 decision,” says an expert blog post by the Natural Resources Defense Council (NRDC). “Because that action would have allowed for dangerous soot exposures to fester for another five years before any new look at the science, NRDC took action and filed a lawsuit against EPA on the last day of the Trump administration, demanding that the agency reconsider its flawed decision. In June 2021, the Biden EPA announced its plan to reopen the decision, setting the stage for this year’s proposal.”

However, the state AGs disagree that the EPA has the authority to lower the NAAQS.

“In sum, the EPA’s ‘new science’ simply does not demonstrate that the current NAAQS are inadequate to protect public health,” the AGs’ comment letter asserts. “The EPA is required to consider evolving science, but the agency is not required to make changes every time it goes through such a consideration. Indeed, there will certainly be times—as in 2020 and now—when the science indicates that the current NAAQS are requisite to protect public health. Being ‘requisite to protect the public health’ does not require standards that enable ‘a world that is free from all risk.’ And it certainly doesn’t mean the Biden Administration can use it to ram through the President’s climate change policies.”

The AGs’ letter also details the potential harm to state economies should the proposed rule be finalized as is.

“First, the Proposed Rule will devastate economic development. The lower the NAAQS standard, the more areas of the country the EPA will consider out of attainment. And being designated a nonattainment area has serious and costly implications. For instance, one study noted that over a fifteen-year period, counties targeted by [CAA] regulations lost $37 billion in capital stock and $75 billion of industrial output. Because the EPA fails to articulate a pathway to compliance with the lower standards, the Proposed Rule raises the serious possibility that compliance will require closing existing manufacturing and industrial facilities. … Second, the Proposed Rule will eliminate jobs. From 1972–1987, counties targeted by [CAA] regulations lost almost 600,000 jobs.

Is it enough?

“Soot, also known as particulate matter, is an especially harmful type of air pollution, since the small particles easily lodge in human lungs where they can trigger asthma attacks, heart disease, lung disease and cancer. Soot pollution affects millions of people each year,” says Environment America. “According to a 2021 report, Trouble in the Air, more than one in six Americans (58.4 million people) suffered through more than 100 days of elevated air pollution in 2020. And 206 million Americans – more than 60 percent – were exposed to over a month of elevated soot pollution. In the U.S., the largest human-caused sources of soot pollution are fossil fuels – coal, oil and gas – burned for electricity and transportation.”

According to EPA estimates, strengthening the primary annual PM2.5 standard to a level of 9 µg per cubic meter—the lower end of the proposed range—would:

• Prevent up to 4,200 premature deaths per year.
• Prevent 270,000 lost workdays per year.
• Result in as much as $43 billion in net health benefits in 2032.

Lowering the annual PM2.5 standard to 9 µg isn’t enough to please activists.

The current proposed regulation “didn’t go as far as EPA’s Clean Air Scientific Advisory Committee (CASAC) recommendation (down to 8 micrograms). The agency’s analysis indicated that lowering the standard from 12 to 9 (micrograms) would result in 4,200 fewer deaths each year from soot air pollution, while lowering it only to 10 would result in about 1,900 fewer annual deaths,” adds the NRDC blog post. “For example, an NRDC analysis published in January shows that lowering the annual soot limits to that level would protect an additional 57 million people from contaminated air; a weaker limit would only shield an additional 6.5 million people. … Additional research confirms the basic finding that the current soot limits should be strengthened to reduce health risks. Specifically, daily and annual soot limits should be set at levels that are protective of the populations who are most vulnerable to pollution. For soot, EPA has already acknowledged that the most at-risk populations today are Black and Hispanic populations.”

The Center for American Progress (CAP) agrees the PM2.5 standards should be lowered to 8 µg per cubic meter.

In comments submitted in response to the EPA’s proposed rule, the CAP states, “The benefits of lowering soot emissions greatly outweigh the costs. The EPA estimates that lowering the limit to 8 micrograms per cubic meter could cost over a billion dollars. But that cost pales in comparison to the savings from reducing deaths and illness. Even lower-end estimates find that the combined economic value of avoided deaths and illness associated with a limit of 8 micrograms per cubic meter would be over $127 billion in net benefits over 10 years. These savings do not include benefits to health and well-being. The human cost of unchecked air pollution itself is unacceptable, and the benefits of strong standards are undeniable.”