Tracking Submicron Particulate Matter: A New Era in Air Quality Research

June 14, 2025
Tracking Submicron Particulate Matter: A New Era in Air Quality Research

In an unprecedented study published in The Lancet Planetary Health, researchers from Washington University in St. Louis have tracked the concentrations of submicron particulate matter (PM 1) across the contiguous United States over the past 25 years. This research sheds light on a significant yet often overlooked aspect of air pollution that contributes to health problems and is linked to approximately 50,000 annual deaths in the U.S. alone.

Particulate matter (PM), particularly PM 2.5 and PM 1, poses severe risks to human health due to their ability to penetrate deep into the respiratory system. PM 2.5 refers to particles less than 2.5 microns in diameter, while PM 1 is even smaller, measuring less than 1 micron. According to Dr. Randall Martin, the Raymond R. Tucker Distinguished Professor of Energy, Environmental and Chemical Engineering at Washington University and co-author of the study, understanding the sources and health impacts of PM 1 is crucial for public health regulation and intervention strategies.

Historically, the Environmental Protection Agency (EPA) established air quality standards for PM 2.5 in 1997, primarily due to the lack of health impact studies for PM 1. Dr. Jay Turner, the James McKelvey Professor of Engineering Education and co-author of the study, emphasized that this new dataset provides a comprehensive national overview that could influence future regulatory measures targeting PM 1.

The researchers utilized advanced satellite remote sensing and atmospheric modeling techniques to quantify PM 1 levels. Chi Li, research assistant professor in Martin's atmospheric composition analysis group and the study’s lead author, stated, "These estimations will enable further investigation into the health and environmental effects of submicron particles."

Findings from the study reveal a significant decline in average PM 1 levels across the U.S. from 1998 to 2022, attributed to stringent environmental regulations such as the Clean Air Act. However, this progress has plateaued since 2010, largely due to increased wildfire activity, which contributes to the formation of PM 1. The study highlights the need for future pollution controls to address emerging sources that are not directly linked to fossil fuels.

As air pollution is a pressing global issue, the data gathered from this research positions the U.S. to better understand and manage PM 1 levels, as other countries like China have already established tracking systems for submicron particles. Dr. Martin remarked, "This dataset offers unprecedented information for the United States about an important pollutant for which few other measurements exist."

The implications of this research extend beyond mere data collection; they underscore the urgent need for policymakers to consider PM 1 in future health impact assessments. As the ongoing climate crisis exacerbates air quality issues, understanding the full spectrum of particulate matter pollution will be critical in safeguarding public health and the environment. The next steps involve collaboration with epidemiologists to further assess the health outcomes associated with PM 1 exposure, paving the way for more effective air quality regulations in the years to come.

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air pollutionparticulate matterPM 1PM 2.5Washington UniversityRandall MartinJay TurnerChi Lienvironmental healthEPA regulationswildfire smokehealth impactsair quality standardssatellite remote sensingatmospheric modelingsubmicron particlesClean Air ActU.S. air qualitypublic healthpollution controlenvironmental sciencehealth outcomesNational Institute of Environmental Health SciencesThe Lancet Planetary Healthpollutant trackingairborne toxinsenvironmental policyemission sourcesclimate changeepidemiological studiespollution dataset

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