Impact of Emission Standards on Fine Particulate Matter Toxicity: A Long-Term Analysis in Los Angeles
This study examines long-term trends in fine particulate matter (PM<sub>2.5</sub>) composition and oxidative potential in Los Angeles based on data from the University of Southern California’s Particle Instrumentation Unit, with chemical composition retrieved from the EPA’s Air Quality S...
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MDPI AG
2025-02-01
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| Online Access: | https://www.mdpi.com/2305-6304/13/2/140 |
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| author | Mohammad Mahdi Badami Yashar Aghaei Constantinos Sioutas |
| author_facet | Mohammad Mahdi Badami Yashar Aghaei Constantinos Sioutas |
| author_sort | Mohammad Mahdi Badami |
| collection | DOAJ |
| description | This study examines long-term trends in fine particulate matter (PM<sub>2.5</sub>) composition and oxidative potential in Los Angeles based on data from the University of Southern California’s Particle Instrumentation Unit, with chemical composition retrieved from the EPA’s Air Quality System (AQS). While regulatory interventions have reduced PM<sub>2.5</sub> mass concentration and primary combustion-related components, our findings reveal a more complex toxicity pattern. From 2001 to 2008, the PM<sub>2.5</sub> oxidative potential, measured via the dithiothreitol (DTT) assay, declined from ~0.84 to ~0.16 nmol/min/m<sup>3</sup> under stringent tailpipe controls. However, after this initial decline, PM<sub>2.5</sub> DTT stabilized and gradually increased from ~0.35 in 2012 to ~0.97 nmol/min/m<sup>3</sup> by 2024, reflecting the growing influence of non-tailpipe emissions such as brake/tire wear. Metals, such as iron (Fe, ~150 ng/m<sup>3</sup>) and zinc (Zn, ~10 ng/m<sup>3</sup>), remained relatively stable as organic and elemental carbon (OC and EC) declined, resulting in non-tailpipe contributions dominating PM<sub>2.5</sub> toxicity. Although PM<sub>2.5</sub> mass concentrations were effectively reduced, the growing contribution of non-tailpipe emissions (e.g., brake/tire wear and secondary organic aerosols) underscores the limitations of mass-based standards and tailpipe-focused strategies. Our findings emphasize the need to broaden regulatory strategies, targeting emerging sources that shape PM<sub>2.5</sub> composition and toxicity and ensuring more improvements in public health outcomes. |
| format | Article |
| id | doaj-art-340eea4cb3f54029ba12d42cec65a9c7 |
| institution | OA Journals |
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| language | English |
| publishDate | 2025-02-01 |
| publisher | MDPI AG |
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| series | Toxics |
| spelling | doaj-art-340eea4cb3f54029ba12d42cec65a9c72025-08-20T02:04:05ZengMDPI AGToxics2305-63042025-02-0113214010.3390/toxics13020140Impact of Emission Standards on Fine Particulate Matter Toxicity: A Long-Term Analysis in Los AngelesMohammad Mahdi Badami0Yashar Aghaei1Constantinos Sioutas2Department of Civil and Environmental Engineering, University of Southern California, Los Angeles, CA 90089, USADepartment of Civil and Environmental Engineering, University of Southern California, Los Angeles, CA 90089, USADepartment of Civil and Environmental Engineering, University of Southern California, Los Angeles, CA 90089, USAThis study examines long-term trends in fine particulate matter (PM<sub>2.5</sub>) composition and oxidative potential in Los Angeles based on data from the University of Southern California’s Particle Instrumentation Unit, with chemical composition retrieved from the EPA’s Air Quality System (AQS). While regulatory interventions have reduced PM<sub>2.5</sub> mass concentration and primary combustion-related components, our findings reveal a more complex toxicity pattern. From 2001 to 2008, the PM<sub>2.5</sub> oxidative potential, measured via the dithiothreitol (DTT) assay, declined from ~0.84 to ~0.16 nmol/min/m<sup>3</sup> under stringent tailpipe controls. However, after this initial decline, PM<sub>2.5</sub> DTT stabilized and gradually increased from ~0.35 in 2012 to ~0.97 nmol/min/m<sup>3</sup> by 2024, reflecting the growing influence of non-tailpipe emissions such as brake/tire wear. Metals, such as iron (Fe, ~150 ng/m<sup>3</sup>) and zinc (Zn, ~10 ng/m<sup>3</sup>), remained relatively stable as organic and elemental carbon (OC and EC) declined, resulting in non-tailpipe contributions dominating PM<sub>2.5</sub> toxicity. Although PM<sub>2.5</sub> mass concentrations were effectively reduced, the growing contribution of non-tailpipe emissions (e.g., brake/tire wear and secondary organic aerosols) underscores the limitations of mass-based standards and tailpipe-focused strategies. Our findings emphasize the need to broaden regulatory strategies, targeting emerging sources that shape PM<sub>2.5</sub> composition and toxicity and ensuring more improvements in public health outcomes.https://www.mdpi.com/2305-6304/13/2/140non-tailpipe emissionsaerosolmetals and trace elementsDTT assayair pollution regulations |
| spellingShingle | Mohammad Mahdi Badami Yashar Aghaei Constantinos Sioutas Impact of Emission Standards on Fine Particulate Matter Toxicity: A Long-Term Analysis in Los Angeles Toxics non-tailpipe emissions aerosol metals and trace elements DTT assay air pollution regulations |
| title | Impact of Emission Standards on Fine Particulate Matter Toxicity: A Long-Term Analysis in Los Angeles |
| title_full | Impact of Emission Standards on Fine Particulate Matter Toxicity: A Long-Term Analysis in Los Angeles |
| title_fullStr | Impact of Emission Standards on Fine Particulate Matter Toxicity: A Long-Term Analysis in Los Angeles |
| title_full_unstemmed | Impact of Emission Standards on Fine Particulate Matter Toxicity: A Long-Term Analysis in Los Angeles |
| title_short | Impact of Emission Standards on Fine Particulate Matter Toxicity: A Long-Term Analysis in Los Angeles |
| title_sort | impact of emission standards on fine particulate matter toxicity a long term analysis in los angeles |
| topic | non-tailpipe emissions aerosol metals and trace elements DTT assay air pollution regulations |
| url | https://www.mdpi.com/2305-6304/13/2/140 |
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