BACKGROUND: We examined the association between acute cardiovascular disease (CVD) events and wildfire air pollution in California in 2018. METHODS: The study included adult (≥18 years) members of Kaiser Permanente Northern California, an integrated health care system. Outcomes included CVD events (hospitalizations for acute myocardial infarction, heart failure, or stroke, and CVD death) and death from any cause. Fine particulate air pollution (particulate matter <
2.5 microns in diameter
PM RESULTS: Our study included 3.2 million adults with a total follow-up of 587.9 million person-days. High PM CONCLUSIONS: There was some evidence of increased rates of CVD events and death during wildfires, but results were inconsistent. With ongoing climate change, large wildfires are a pressing public health concern and future work is needed to understand differences in health outcomes by wildfire.