PROJECT SUMMARY Open burning of agricultural fields to remove crop residue left after harvesting remains a common agricultural practice and an underappreciated source of air pollution exposure worldwide. Globally, agricultural burning is widespread and accounts for nearly half as much biomass burned as wildfires. Across the continental US, agricultural burning amounts to an estimated ~3-5.8 million acres burned annually and approximately 15.5 million people within the US are affected by crop burning and related smoke exposures. While prior research has identified adverse health impacts from wildfire events and domestic biomass burning, there is a paucity of research on the specific impact of agricultural burning on health in US populations, despite evidence that it is a widespread practice associated with release of toxic air pollutants. As part of our current work in Imperial County, we have focused on understanding the links between air quality and local sources of particulate matter (PM) exposure with children’s respiratory health. We established the “Assessing Imperial Valley Respiratory Health and the Environment (AIRE) cohort (MPI Farzan/Johnston 1R01ES029598), a cohort of 550 school-age children with repeated respiratory health assessments. The overall goal of the AIRE study is to develop a community- academic partnership to determine the health effects of childhood exposures to wind-blown PM and inform public health action in the Imperial Valley. In response to growing community concerns to explore the impacts of complex air pollution mixtures in the regions, we propose to integrate exposure metrics on agricultural burning in Imperial Valley into our assessment of children’s respiratory health in the AIRE study. Using a novel community monitoring network together with filter-based PM monitoring, we will estimate contributions of daily agricultural burn activity to PM concentrations. This exposure data will be leveraged in the larger epidemiological study to assess the association between agricultural burning and children’s respiratory health symptoms. Our study aims to: 1) Quantify children’s PM exposures through the characterization of spatial and temporal variations in agricultural burning in AIRE communities from 2008-2021, by examining the relationship between agricultural burning records with ambient PM concentrations and composition by leveraging an existing community-based air monitoring network and by developing a source-apportionment model using hallmarks of agricultural burning; and 2) Assess the relationship between agricultural burning and children’s respiratory health to exposure whether exposure to agricultural burning is associated with asthma incidence and exacerbations, respiratory symptoms and lung function in the established elementary school-aged AIRE cohort. The proposed work will incorporate agricultural burning exposures that may impact air quality and children’s health, allowing us to more fully discriminate betwee...