Chapter 13 of the Health Effects of Climate Change (HECC) in the UK: 2023 report. Sunlight has numerous benefits for health, but excessive exposure can cause sunburn and increase risk of some cancers. Chapter 13 examines the relationship between exposure to solar radiation and health, and how our changing climate may affect these risks. The chapter provides an updated synthesis of new evidence published since the last ‘Health Effects of Climate Change in the UK’ report and was written by scientific experts from the UK Health Security Agency (UKHSA).