Pollen allergies have been on the rise in cities, where anthropogenic disturbances, warmer climate and introduced species are shaping novel urban ecosystems. Yet, the allergenic potential of these urban ecosystems, in particular spontaneous vegetation outside parks and gardens, remains poorly known. We quantified the allergenic properties of 56 dry grasslands along a double gradient of urbanisation and plant invasion in Berlin (Germany). 30% of grassland species were classified as allergenic, most of them being natives. Urbanisation was associated with an increase in abundance and diversity of pollen allergens, mainly driven by an increase in allergenic non-native plants. While not inherently more allergenic than native plants, the pool of non-natives contributed a larger biochemical diversity of allergens and flowered later than natives, creating a broader potential spectrum of allergy. Managing novel risks to urban public health will involve not only targeted action on allergenic non-natives, but also policies at the habitat scale favouring plant community assembly of a diverse, low-allergenicity vegetation. Similar approaches could be easily replicated in other cities to provide a broad quantification and mapping of urban allergy risks and drivers.

花粉过敏在城市中呈上升趋势，人为干扰、气候变暖和外来物种正在塑造新的城市生态系统。然而，这些城市生态系统的致敏潜力，特别是公园和花园外的自发植被，仍然鲜为人知。我们在柏林（德国）沿城市化和植物入侵的双重梯度量化了 56 个干燥草原的过敏原特性。30% 的草原物种被归类为致敏性，其中大多数是本地人。城市化与花粉过敏原的丰度和多样性增加有关，主要是由致敏性非本地植物的增加所驱动。虽然在本质上并不比本地植物更容易过敏，但非本地植物库贡献了更大的过敏原生化多样性，并且比本地植物更晚开花，创造更广泛的潜在过敏范围。管理对城市公共卫生的新风险不仅涉及对过敏原的非本地人采取有针对性的行动，而且还涉及栖息地范围内有利于植物群落组装多样化、低过敏性植被的政策。类似的方法可以很容易地在其他城市复制，以提供对城市过敏风险和驱动因素的广泛量化和映射。