Reconsideration of the National Ambient Air Quality Standards for Particulate Matter

<RULE> ENVIRONMENTAL PROTECTION AGENCY <CFR>40 CFR Parts 50, 53, and 58</CFR> <DEPDOC>[EPA-HQ-OAR-2015-0072; FRL-8635-02-OAR]</DEPDOC> <RIN>RIN 2060-AV52</RIN> <SUBJECT>Reconsideration of the National Ambient Air Quality Standards for Particulate Matter</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Environmental Protection Agency (EPA). <HD SOURCE="HED">ACTION:</HD> Final rule. <SUM> <HD SOURCE="HED">SUMMARY:</HD> Based on the Environmental Protection Agency's (EPA's) reconsideration of the air quality criteria and the national ambient air quality standards (NAAQS) for particulate matter (PM), the EPA is revising the primary annual PM <E T="52">2.5</E> standard by lowering the level from 12.0 µg/m <SU>3</SU> to 9.0 µg/m <SU>3</SU> . The Agency is retaining the current primary 24-hour PM <E T="52">2.5</E> standard and the primary 24-hour PM <E T="52">10</E> standard. The Agency also is not changing the secondary 24-hour PM <E T="52">2.5</E> standard, secondary annual PM <E T="52">2.5</E> standard, and secondary 24-hour PM <E T="52">10</E> standard at this time. The EPA is also finalizing 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. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> This final rule is effective May 6, 2024. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> The EPA has established a docket for this action under Docket ID No. EPA-HQ-OAR-2015-0072. All documents in the docket are listed on the <E T="03">https://www.regulations.gov</E> website. Although listed in the index, some information is not publicly available, <E T="03">e.g.,</E> CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, is not placed on the internet and will be publicly available only in hard copy form. Publicly available docket materials are available electronically through <E T="03">https://www.regulations.gov.</E> <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Dr. Lars Perlmutt, Health and Environmental Impacts Division, Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Mail Code C539-04, Research Triangle Park, NC 27711; telephone: (919) 541-3037; fax: (919) 541-5315; email: <E T="03">perlmutt.lars@epa.gov.</E> </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> <HD SOURCE="HD1">Table of Contents</HD> The following topics are discussed in this preamble: <EXTRACT> <FP SOURCE="FP-2">Executive Summary</FP> <FP SOURCE="FP-2">I. Background</FP> <FP SOURCE="FP1-2">A. Legislative Requirements</FP> <FP SOURCE="FP1-2">B. Related PM Control Programs</FP> <FP SOURCE="FP1-2">C. Review of the Air Quality Criteria and Standards for Particulate Matter</FP> <FP SOURCE="FP1-2">1. Reviews Completed in 1971 and 1987</FP> <FP SOURCE="FP1-2">2. Review Completed in 1997</FP> <FP SOURCE="FP1-2">3. Review Completed in 2006</FP> <FP SOURCE="FP1-2">4. Review Completed in 2012</FP> <FP SOURCE="FP1-2">5. Review Initiated in 2014</FP> <FP SOURCE="FP1-2">a. 2020 Proposed and Final Decisions</FP> <FP SOURCE="FP1-2">b. Reconsideration of the 2020 PM NAAQS Final Action</FP> <FP SOURCE="FP1-2">D. Air Quality Information</FP> <FP SOURCE="FP1-2">1. Distribution of Particle Size in Ambient Air</FP> <FP SOURCE="FP1-2">2. Sources and Emissions Contributing to PM in the Ambient Air</FP> <FP SOURCE="FP1-2">3. Monitoring of Ambient PM</FP> <FP SOURCE="FP1-2">4. Ambient Concentrations and Trends</FP> <FP SOURCE="FP1-2"> a. PM <E T="52">2.5</E> Mass </FP> <FP SOURCE="FP1-2"> b. PM <E T="52">2.5</E> Components </FP> <FP SOURCE="FP1-2"> c. PM <E T="52">10</E> </FP> <FP SOURCE="FP1-2"> d. PM <E T="52">10-2.5</E> </FP> <FP SOURCE="FP1-2">e. UFP</FP> <FP SOURCE="FP1-2"> 5. Characterizing Ambient PM <E T="52">2.5</E> Concentrations for Exposure </FP> <FP SOURCE="FP1-2"> a. Predicted Ambient PM <E T="52">2.5</E> and Exposure Based on Monitored Data </FP> <FP SOURCE="FP1-2"> b. Comparison of PM <E T="52">2.5</E> Fields in Estimating Exposure and Relative to Design Values </FP> <FP SOURCE="FP1-2">6. Background PM</FP> <FP SOURCE="FP-2"> II. Rationale for Decisions on the Primary PM <E T="52">2.5</E> Standards </FP> <FP SOURCE="FP1-2">A. Introduction</FP> <FP SOURCE="FP1-2">1. Background on the Current Standards</FP> <FP SOURCE="FP1-2">2. Overview of the Health Effects Evidence</FP> <FP SOURCE="FP1-2">a. Nature of Effects</FP> <FP SOURCE="FP1-2">i. Mortality</FP> <FP SOURCE="FP1-2">ii. Cardiovascular Effects</FP> <FP SOURCE="FP1-2">iii. Respiratory Effects</FP> <FP SOURCE="FP1-2">iv. Cancer</FP> <FP SOURCE="FP1-2">v. Nervous System Effects</FP> <FP SOURCE="FP1-2">vi. Other Effects</FP> <FP SOURCE="FP1-2">b. Public Health Implications and At-Risk Populations</FP> <FP SOURCE="FP1-2"> c. PM <E T="52">2.5</E> Concentrations in Key Studies Reporting Health Effects </FP> <FP SOURCE="FP1-2"> i. PM <E T="52">2.5</E> Exposure Concentrations Evaluated in Experimental Studies </FP> <FP SOURCE="FP1-2"> ii. Ambient PM <E T="52">2.5</E> Concentrations in Locations of Epidemiologic Studies </FP> <FP SOURCE="FP1-2">d. Uncertainties in the Health Effects Evidence</FP> <FP SOURCE="FP1-2">3. Summary of Exposure and Risk Estimates</FP> <FP SOURCE="FP1-2">a. Key Design Aspects</FP> <FP SOURCE="FP1-2">b. Key Limitations and Uncertainties</FP> <FP SOURCE="FP1-2">c. Summary of Risk Estimates</FP> <FP SOURCE="FP1-2"> B. Conclusions on the Primary PM <E T="52">2.5</E> Standards </FP> <FP SOURCE="FP1-2">1. CASAC Advice</FP> <FP SOURCE="FP1-2">2. Basis for the Proposed Decision</FP> <FP SOURCE="FP1-2">3. Comments on the Proposed Decision</FP> <FP SOURCE="FP1-2">4. Administrator's Conclusions</FP> <FP SOURCE="FP1-2"> C. Decisions on the Primary PM <E T="52">2.5</E> Standards </FP> <FP SOURCE="FP-2"> III. Rationale for Decisions on the Primary PM <E T="52">10</E> Standard </FP> <FP SOURCE="FP1-2">A. Introduction</FP> <FP SOURCE="FP1-2">1. Background on the Current Standard</FP> <FP SOURCE="FP1-2">2. Overview of Health Effects Evidence</FP> <FP SOURCE="FP1-2">a. Nature of Effects</FP> <FP SOURCE="FP1-2">i. Mortality</FP> <FP SOURCE="FP1-2">ii. Cardiovascular Effects</FP> <FP SOURCE="FP1-2">iii. Respiratory Effects</FP> <FP SOURCE="FP1-2">iv. Cancer</FP> <FP SOURCE="FP1-2">v. Metabolic Effects</FP> <FP SOURCE="FP1-2">vi. Nervous System Effects</FP> <FP SOURCE="FP1-2"> B. Conclusions on the Primary PM <E T="52">10</E> Standard </FP> <FP SOURCE="FP1-2">1. CASAC Advice</FP> <FP SOURCE="FP1-2">2. Basis for the Proposed Decision</FP> <FP SOURCE="FP1-2">3. Comments on the Proposed Decision</FP> <FP SOURCE="FP1-2">4. Administrator's Conclusions</FP> <FP SOURCE="FP1-2"> C. Decisions on the Primary PM <E T="52">10</E> Standard </FP> <FP SOURCE="FP-2">IV. Communication of Public Health</FP> <FP SOURCE="FP1-2">A. Air Quality Index Overview</FP> <FP SOURCE="FP1-2"> B. Air Quality Index Category Breakpoints for PM <E T="52">2.5</E> </FP> <FP SOURCE="FP1-2">1. Summary of Proposed Revisions</FP> <FP SOURCE="FP1-2">a. Air Quality Index Values of 50, 100, and 150</FP> <FP SOURCE="FP1-2">b. Air Quality Index Values of 200 and Above</FP> <FP SOURCE="FP1-2">2. Summary of Significant Comments on Proposed Revisions</FP> <FP SOURCE="FP1-2">a. Air Quality Index Values of 50, 100, and 150</FP> <FP SOURCE="FP1-2">b. Air Quality Index Values of 200 and Above</FP> <FP SOURCE="FP1-2">c. Other Comments</FP> <FP SOURCE="FP1-2">3. Summary of Final Revisions</FP> <FP SOURCE="FP1-2"> C. Air Quality Index Category Breakpoints for PM <E T="52">10</E> </FP> <FP SOURCE="FP1-2">D. Air Quality Index Reporting</FP> <FP SOURCE="FP1-2">1. Summary of Proposed Revisions</FP> <FP SOURCE="FP1-2">2. Summary of Significant Comments on Proposed Revisions</FP> <FP SOURCE="FP1-2">3. Summary of Final Revisions</FP> <FP SOURCE="FP-2">V. Rationale for Decisions on the Secondary PM Standards</FP> <FP SOURCE="FP1-2">A. Introduction</FP> <FP SOURCE="FP1-2">1. Background on the Current Standards</FP> <FP SOURCE="FP1-2">a. Non-Visibility Effects</FP> <FP SOURCE="FP1-2">b. Visibility Effects</FP> <FP SOURCE="FP1-2">2. Overview of Welfare Effects Evidence</FP> <FP SOURCE="FP1-2">a. Nature of Effects</FP> <FP SOURCE="FP1-2">i. Visibility</FP> <FP SOURCE="FP1-2">ii. Climate</FP> <FP SOURCE="FP1-2">iii. Materials</FP> <FP SOURCE="FP1-2">3. Summary of Air Quality and Quantitative Information</FP> <FP SOURCE="FP1-2">a. Visibility Effects</FP> <FP SOURCE="FP1-2"> i. Target Level of Protection in Terms of a PM <E T="52">2.5</E> Visibility Index </FP> <FP SOURCE="FP1-2"> ii. Relationship Between the PM <E T="52">2.5</E> Visibility Index and the Current Secondary 24-Hour PM <E T="52">2.5</E> Standard </FP> <FP SOURCE="FP1-2">b. Non-Visibility Effects</FP> <FP SOURCE="FP1-2">B. Conclusions on the Secondary PM Standards</FP> <FP SOURCE="FP1-2">1. CASAC Advice</FP> <FP SOURCE="FP1-2">2. Basis for the Proposed Decision</FP> <FP SOURCE="FP1-2">3. Comments on the Proposed Decision</FP> <FP SOURCE="FP1-2">4. Administrator's Conclusions</FP> <FP SOURCE="FP1-2">C. Decisions on the Secondary PM Standards</FP> <FP SOURCE="FP-2">VI. Interpretation of the NAAQS for PM</FP> <FP SOURCE="FP1-2">A. Amendments to Appendix K: Interpretation of the NAAQS for Particulate Matter</FP> <FP SOURCE="FP1-2"> B. Amendments to Appendix N: Interpretation of the NAAQS for PM <E T="52">2.5</E> </FP> <FP SOURCE="FP-2"> VII. Amendments to Ambient Monitoring and Quality Assurance Requirements </FP> <FP SOURCE="FP1-2"> A. Amendment to 40 CFR Part 50 (Appendix L): Reference Method for the Determination of Fine Particulate Matter as PM <E T="52">2.5</E> in the Atmosphere—Addition of the Tisch Cyclone as an Ap ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 1580k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━