Climate change poses a significant threat to human health. In recent years, Californians have encountered frequent extreme heat and air pollution events, exposure to which increases the risk of several medical conditions, both acute and chronic. Blue Shield of California recently collaborated with Milliman to investigate the impact extreme heat and poor air quality on healthcare utilization among the insured population in California in the years 2017-2019. The main sections of the paper present the following:

• Description of the data sources used in the study
• Methodology of the study
• Results and implications