Abstract
The allergy and asthma epidemic in urban societies following World War II is mostly caused by changes in the environment, diet and lifestyle. Disconnection of urban populations from the wider environment has reduced the protective factors building up immunological resilience. The European Academy of Allergy and Clinical Immunology (EAACI) guidelines on greenness impact on allergy and asthma follow the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach and provide eight recommendations encouraging greenness exposure to support immune health. Controlled follow-up studies are still scarce, and the strength of evidence is generally low or moderate at best. For primary prevention of allergy and asthma, most of the evidence indicates beneficial effects. Exposure is also useful for secondary prevention. Asthma patients may feel better and need less medication by combining green space exposure with physical activity. During the high-pollen season, effective seasonal medication is necessary for patients with pollen allergy. In urban planning, implementing appropriate green infrastructure and easy access to green space promotes immune health and reduces risks of air pollution and heatwaves. These EAACI guidelines are the first recommendations highlighting the importance of urban green spaces on immune health and call for prioritising innovative research in this field.