This paper investigates the impact of airborne pollen on serious and fatal traffic accidents in the UK. Using daily county-level data from UK Met Office reporting sites spanning 2013–2023, I find that higher pollen concentrations cause an increase in severe traffic accidents. The effect seems to be driven by tree pollen in particular. The results are robust to a range of weather and air pollution controls and are further validated using simulated pollen data from Ambee (2016–2022). These findings underscore the role of seasonal health-related factors in shaping road safety outcomes. Additionally, I explore the use of thermal inversion as an instrumental variable for pollen exposure and raise serious concerns about the validity of the exogeneity assumption in this context, with implications for its application in air pollution research.