US and Global Aerosol Speciation Monitoring Networks: Successes and Opportunities

ANN M. DILLNER, University of California, Davis

     Abstract Number: 170
     Working Group: Plenary Lecture Invited by Conference Chair

Abstract
Aerosol monitoring networks are foundational to understanding air quality and its impact on people and the planet. The United States boasts two long-term, filter-based aerosol speciation networks: the Interagency Monitoring of PROtected Visual Environments (IMPROVE) network, which has ~150 monitoring sites in pristine locations and launched in 1989, and the Chemical Speciation Network (CSN), which has ~130 urban and suburban sites and started sampling in 2000. More recently, the US began supporting two international particle speciation monitoring networks: the Surface PARTiculate mAtter Network (SPARTAN) and the Multi-Angle Imager for Aerosols (MAIA) satellite mission, which together have ~35 urban sites globally. Finally, in 2024, the Atmospheric Science and Chemistry mEasurement NeTwork (ASCENT) started real-time sampling at twelve US urban and rural sites using high-time-resolution instruments to measure aerosol speciation and particle size distributions.

In this presentation, I will highlight the value of particle speciation monitoring networks, the challenges in maintaining consistency over time, and the opportunities that real-time, high-time-resolution data provides. I will illustrate the value of long-term IMPROVE and CSN data for tracking trends in composition due to regulations and other factors, validating atmospheric models, and providing historical context for field campaigns and major pollution events. I will also discuss efforts by SPARTAN and MAIA to provide speciated aerosol data at international sites where aerosol monitoring is sparse but health impacts are high. Finally, I will describe the opportunities provided by ASCENT’s real-time, high-time-resolution monitoring, such as the rapid release of data following the January 2025 Los Angeles wildfires.