ABSTRACT (RESEARCH PROJECT) Extreme heat and wildfire smoke events are projected to increase in frequency. They are currently impacting health in California and around the world; however, health effects of co-occurring extreme heat and high- intensity wildfire smoke at the same time are understudied. Disproportionately impacted communities are the most exposed to these climate-sensitive events, the most sensitive to their adverse effects, and the least likely to have the economic, social, or political resources necessary to prepare for or recover from such events. Inequities in exposures translate to inequities in health, and we will approach this climate health challenge with data-driven and community-engaged strategies to understand and mitigate exposures in highly impacted communities. We propose to investigate, in the broadest and largest study to date, the impact of co-occurring heat waves and wildfire smoke on health effects across the life course including pregnancy outcomes, infectious diseases, respiratory conditions, and cardiovascular disease. Selected health outcomes will include low birth weight, preterm birth, and gestational hypertension (pregnancy), healthcare utilization, lower respiratory tract infections (LRTI), and asthma (pediatric), and healthcare utilization, LRTI, asthma, chronic obstructive lung disease, myocardial infarction, and heart failure (adult). We will investigate how these relationships may be modified by multiple social and structural conditions at the small-scale level including the built environment and insecurities in material needs like food, housing, income, and healthcare. We will identify promising social and structural factors to model and target for intervention design and build upon community- partnered work to mitigate exposures and health effects attributable to extreme heat and wildfire smoke events. Our multidisciplinary team of climate scientists with clinical, environmental, and epidemiological expertise will collaborate to identify climate-related vulnerabilities in the structural and social context in disproportionately impacted communities that can be translated into equitable solutions for health through community-collaborative research partnerships. Our aims are to: 1) Examine health effects of co-occurring extreme heat and wildfire smoke exposure by social and structural factors (e.g., the built environment and insecurities in material needs like food, housing, income, and healthcare) across California at the zip code level; 2) Simulate the impact of community-preferred and modifiable social and structural mitigation scenarios on health effects during co-occurring extreme heat and wildfire smoke exposure and present to community partners; and 3) Co-design and prototype social and structural interventions to mitigate the health effects of co- occurring extreme heat and wildfire smoke exposure. Our research project will provide the ECO-Health Center with integrated large-scale climate and he...