Seasonal allergies affect over 400 million people globally, yet the broader economic consequences of pollen exposure remain understudied. Evidence from Japan’s ambulance records suggests that high-pollen days are associated with increases in accidents, including traffic accidents and work-related injuries, which may reflect impaired cognitive performance. Retail scanner data and cellphone mobility records indicate that individuals already engage in avoidance behaviors, such as purchasing allergy products and limiting outdoor activities on weekends. This suggests that relying on individual self-protection may be insufficient to offset these risks, and thus greater government intervention may be warranted to mitigate pollen-related harm.