One hundred environmental organizations transmitted an April 21st letter to the United States Environmental Protection Agency (“EPA”) Administrator asking that the federal agency:
…maintain and promptly implement a vital, lifesaving protection—the National Ambient Air Quality Standard for fine particulate matter (PM2.5 or soot) that was established in 2024.
The environmental organizations oppose and express concern due to an EPA announcement that the agency is considering revisiting the revised the National Ambient Air Quality Standard (“NAAQS”) that was set for PM2.5 in 2024.
Particulate matter is a generic term for a broad class of chemically and physically diverse substances that exist as discreet particles (liquid droplets or solids) over a wide range of sizes. It is composed of two major components.
Larger particulates (PM10) are generally the result of mechanical, evaporative, and suspension processes. Particulates designated PM2.5 typically consist of sulfates, nitrates, elemental carbon, organic carbon, compounds or metals. Because of their small size, these particulates can remain in the air for a significant period of time.
Section 108 and 109 of the Clean Air Act require that EPA identify air pollutants utilizing certain criteria and set NAAQS for each. Particulates are one of the six air pollutants currently designated as criteria air pollutants, and subject to NAAQS. Section 109 requires that EPA promulgate primary NAAQS for the pollutants identified under Section 108.
Section 109(d)(1) of the Clean Air Act mandates a periodic review of each NAAQS. Depending on the results of the review, EPA must determine whether the existing air quality criteria and NAAQS must be revised. EPA’s previous review and revision of the PM2.5 NAAQS is an example of this review process.
EPA had modified during the Biden Administration the PM2.5 NAAQS to a more restrictive 9 micrograms per cubic meter. The previous PM2.5 standard was 12 micrograms per cubic meter.
The April 21st letter by the environmental organizations puts forth arguments in favor of maintaining the PM2.5 NAAQS that include:
- EPA followed all applicable legal requirements in promulgating the NAAQS.
- The NAAQS is well-supported by science.
- PM 2.5 or soot causes a variety of health problems.
- PM2.5 disproportionately affects Latino, Black, and low-income populations.
- The tightened standard will result in the avoidance of nearly 1 million cases of asthma-related health complications.
A copy of the April 21st letter (which contains a list of organizations who signed it) can be downloaded here.
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